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input_description -distribution {Quantum Espresso} -package PWscf -program pw.x {
toc {}
intro {
@b {Input data format:} { } = optional, [ ] = it depends, | = or
All quantities whose dimensions are not explicitly specified are in
RYDBERG ATOMIC UNITS. Charge is "number" charge (i.e. not multiplied
by e); potentials are in energy units (i.e. they are multiplied by e).
@b BEWARE: TABS, DOS <CR><LF> CHARACTERS ARE POTENTIAL SOURCES OF TROUBLE
Namelists must appear in the order given below.
Comment lines in @i namelists can be introduced by a "!", exactly as in
fortran code. Comments lines in @i cards can be introduced by
either a "!" or a "#" character in the first position of a line.
Do not start any line in @i cards with a "/" character.
Leave a space between card names and card options, e.g.
ATOMIC_POSITIONS (bohr), not ATOMIC_POSITIONS(bohr)
Do not start any line in @i cards with a "/" character.
@b {Structure of the input data:}
===============================================================================
@b &CONTROL
...
@b /
@b &SYSTEM
...
@b /
@b &ELECTRONS
...
@b /
[ @b &IONS
...
@b / ]
[ @b &CELL
...
@b / ]
@b ATOMIC_SPECIES
X Mass_X PseudoPot_X
Y Mass_Y PseudoPot_Y
Z Mass_Z PseudoPot_Z
@b ATOMIC_POSITIONS { alat | bohr | crystal | angstrom | crystal_sg }
X 0.0 0.0 0.0 {if_pos(1) if_pos(2) if_pos(3)}
Y 0.5 0.0 0.0
Z O.0 0.2 0.2
@b K_POINTS { tpiba | automatic | crystal | gamma | tpiba_b | crystal_b | tpiba_c | crystal_c }
if (gamma)
nothing to read
if (automatic)
nk1, nk2, nk3, k1, k2, k3
if (not automatic)
nks
xk_x, xk_y, xk_z, wk
if (tpipa_b or crystal_b in a 'bands' calculation) see Doc/brillouin_zones.pdf
[ @b CELL_PARAMETERS { alat | bohr | angstrom }
v1(1) v1(2) v1(3)
v2(1) v2(2) v2(3)
v3(1) v3(2) v3(3) ]
[ @b OCCUPATIONS
f_inp1(1) f_inp1(2) f_inp1(3) ... f_inp1(10)
f_inp1(11) f_inp1(12) ... f_inp1(nbnd)
[ f_inp2(1) f_inp2(2) f_inp2(3) ... f_inp2(10)
f_inp2(11) f_inp2(12) ... f_inp2(nbnd) ] ]
[ @b CONSTRAINTS
nconstr { constr_tol }
constr_type(.) constr(1,.) constr(2,.) [ constr(3,.) constr(4,.) ] { constr_target(.) } ]
[ @b ATOMIC_FORCES
label_1 Fx(1) Fy(1) Fz(1)
.....
label_n Fx(n) Fy(n) Fz(n) ]
}
#
# namelist CONTROL
#
namelist CONTROL {
var calculation -type CHARACTER {
default { 'scf' }
options {
info {
A string describing the task to be performed. Options are:
}
opt -val 'scf' {}
opt -val 'nscf' {}
opt -val 'bands' {}
opt -val 'relax' {}
opt -val 'md' {}
opt -val 'vc-relax' {}
opt -val 'vc-md' {}
info {
(vc = variable-cell).
}
}
}
var title -type CHARACTER {
default {' '}
info {
reprinted on output.
}
}
var verbosity -type CHARACTER {
default { 'low' }
options {
info {
Currently two verbosity levels are implemented:
}
opt -val 'high' {}
opt -val 'low' {}
info {
@b 'debug' and @b 'medium' have the same effect as @b 'high';
@b 'default' and @b 'minimal' as @b 'low'
}
}
}
var restart_mode -type CHARACTER {
default { 'from_scratch' }
options {
info { Available options are: }
opt -val 'from_scratch' {
From scratch. This is the normal way to perform a PWscf calculation
}
opt -val 'restart' {
From previous interrupted run. Use this switch only if you want to
continue, using the same number of processors and parallelization,
an interrupted calculation. Do not use to start a new one, or to
perform a non-scf calculations. Works only if the calculation was
cleanly stopped using variable @ref max_seconds, or by user request
with an "exit file" (i.e.: create a file "prefix".EXIT, in directory
"outdir"; see variables @ref prefix, @ref outdir). Overrides @ref startingwfc
and @ref startingpot.
}
}
}
var wf_collect -type LOGICAL {
default { .TRUE. }
info {
This flag controls the way wavefunctions are stored to disk :
.TRUE. collect wavefunctions from all processors, store them
into the output data directory "outdir"/"prefix".save
The resulting format is portable to a different number
of processor, or different kind of parallelization
.FALSE. OBSOLETE - NO LONGER IMPLEMENTED
do not collect wavefunctions, leave them in temporary
local files (one per processor). The resulting format
is readable only on the same number of processors and
with the same kind of parallelization used to write it.
Note that this flag has no effect on reading, only on writing.
}
}
var nstep -type INTEGER {
info {
number of molecular-dynamics or structural optimization steps
performed in this run. If set to 0, the code performs a quick
"dry run", stopping just after initialization. This is useful
to check for input correctness and to have the summary printed.
}
default {
1 if @ref calculation == 'scf', 'nscf', 'bands';
50 for the other cases
}
}
var iprint -type INTEGER {
default { write only at convergence }
info {
band energies are written every @i iprint iterations
}
}
var tstress -type LOGICAL {
default { .false. }
info {
calculate stress. It is set to .TRUE. automatically if
@ref calculation == 'vc-md' or 'vc-relax'
}
}
var tprnfor -type LOGICAL {
info {
calculate forces. It is set to .TRUE. automatically if
@ref calculation == 'relax','md','vc-md'
}
}
var dt -type REAL {
default { 20.D0 }
info {
time step for molecular dynamics, in Rydberg atomic units
(1 a.u.=4.8378 * 10^-17 s : beware, the CP code uses
Hartree atomic units, half that much!!!)
}
}
var outdir -type CHARACTER {
default {
value of the ESPRESSO_TMPDIR environment variable if set;
current directory ('./') otherwise
}
info {
input, temporary, output files are found in this directory,
see also @ref wfcdir
}
}
var wfcdir -type CHARACTER {
default { same as @ref outdir }
info {
This directory specifies where to store files generated by
each processor (*.wfc{N}, *.igk{N}, etc.). Useful for
machines without a parallel file system: set @ref wfcdir to
a local file system, while @ref outdir should be a parallel
or network file system, visible to all processors. Beware:
in order to restart from interrupted runs, or to perform
further calculations using the produced data files, you
may need to copy files to @ref outdir. Works only for pw.x.
}
}
var prefix -type CHARACTER {
default { 'pwscf' }
info {
prepended to input/output filenames:
prefix.wfc, prefix.rho, etc.
}
}
var lkpoint_dir -type LOGICAL {
default { .true. }
info {
If .false. a subdirectory for each k_point is not opened
in the "prefix".save directory; Kohn-Sham eigenvalues are
stored instead in a single file for all k-points. Currently
doesn't work together with @ref wf_collect
}
}
var max_seconds -type REAL {
default { 1.D+7, or 150 days, i.e. no time limit }
info {
Jobs stops after @ref max_seconds CPU time. Use this option
in conjunction with option @ref restart_mode if you need to
split a job too long to complete into shorter jobs that
fit into your batch queues.
}
}
var etot_conv_thr -type REAL {
default { 1.0D-4 }
info {
Convergence threshold on total energy (a.u) for ionic
minimization: the convergence criterion is satisfied
when the total energy changes less than @ref etot_conv_thr
between two consecutive scf steps. Note that @ref etot_conv_thr
is extensive, like the total energy.
See also @ref forc_conv_thr - both criteria must be satisfied
}
}
var forc_conv_thr -type REAL {
default { 1.0D-3 }
info {
Convergence threshold on forces (a.u) for ionic minimization:
the convergence criterion is satisfied when all components of
all forces are smaller than @ref forc_conv_thr.
See also @ref etot_conv_thr - both criteria must be satisfied
}
}
var disk_io -type CHARACTER {
default { see below }
options {
info {
Specifies the amount of disk I/O activity:
(only for binary files and xml data file in data directory;
other files printed at each molecular dynamics / structural
optimization step are not controlled by this option )
}
opt -val 'high' {
save charge to disk at each SCF step,
keep wavefunctions on disk (in "distributed" format),
save mixing data as well.
Do not use this option unless you have a good reason to
}
opt -val 'medium' {
save charge to disk at each SCF step,
keep wavefunctions on disk only if more than one k-point,
per process is present, otherwise keep them in memory;
save them to disk only at the end (in "portable" format)
}
opt -val 'low' {
save charge to disk at each SCF step,
keep wavefunctions in memory (for all k-points),
save them to disk only at the end (in "portable" format).
Reduces I/O but increases memory wrt the previous cases
}
opt -val 'nowf' {
save to disk only the xml data file,
never save wavefunctions and charge density
}
opt -val 'none' {
do not save anything to disk
}
info {
@b Default is @b 'low' for the scf case, @b 'medium' otherwise.
Note that the needed RAM increases as disk I/O decreases!
It is no longer needed to specify 'high' in order to be able
to restart from an interrupted calculation (see @ref restart_mode)
but you cannot restart in @ref disk_io=='nowf' or 'none'
}
}
}
var pseudo_dir -type CHARACTER {
default {
value of the $ESPRESSO_PSEUDO environment variable if set;
'$HOME/espresso/pseudo/' otherwise
}
info {
directory containing pseudopotential files
}
}
var tefield -type LOGICAL {
default { .FALSE. }
info {
If .TRUE. a saw-like potential simulating an electric field
is added to the bare ionic potential. See variables @ref edir,
@ref eamp, @ref emaxpos, @ref eopreg for the form and size of
the added potential.
}
}
var dipfield -type LOGICAL {
default { .FALSE. }
info {
If .TRUE. and @ref tefield==.TRUE. a dipole correction is also
added to the bare ionic potential - implements the recipe
of L. Bengtsson, PRB 59, 12301 (1999). See variables @ref edir,
@ref emaxpos, @ref eopreg for the form of the correction. Must
be used ONLY in a slab geometry, for surface calculations,
with the discontinuity FALLING IN THE EMPTY SPACE.
}
}
var lelfield -type LOGICAL {
default { .FALSE. }
info {
If .TRUE. a homogeneous finite electric field described
through the modern theory of the polarization is applied.
This is different from @ref tefield == .true. !
}
}
var nberrycyc -type INTEGER {
default { 1 }
info {
In the case of a finite electric field ( @ref lelfield == .TRUE. )
it defines the number of iterations for converging the
wavefunctions in the electric field Hamiltonian, for each
external iteration on the charge density
}
}
var lorbm -type LOGICAL {
default { .FALSE. }
info {
If @b .TRUE. perform orbital magnetization calculation.
If finite electric field is applied (@ref lelfield==.true.) only Kubo terms are computed
[for details see New J. Phys. 12, 053032 (2010), doi:10.1088/1367-2630/12/5/053032].
The type of calculation is @b 'nscf' and should be performed on an automatically
generated uniform grid of k points.
Works ONLY with norm-conserving pseudopotentials.
}
}
var lberry -type LOGICAL {
default { .FALSE. }
info {
If .TRUE. perform a Berry phase calculation.
See the header of PW/src/bp_c_phase.f90 for documentation.
}
}
var gdir -type INTEGER {
info {
For Berry phase calculation: direction of the k-point
strings in reciprocal space. Allowed values: 1, 2, 3
1=first, 2=second, 3=third reciprocal lattice vector
For calculations with finite electric fields
(@ref lelfield==.true.) "gdir" is the direction of the field.
}
}
var nppstr -type INTEGER {
info {
For Berry phase calculation: number of k-points to be
calculated along each symmetry-reduced string.
The same for calculation with finite electric fields
(@ref lelfield==.true.).
}
}
var lfcpopt -type LOGICAL {
see { fcp_mu }
default { .FALSE. }
info {
If .TRUE. perform a constant bias potential (constant-mu) calculation
for a static system with ESM method. See the header of PW/src/fcp.f90
for documentation.
NB:
- The total energy displayed in 'prefix.out' includes the potentiostat
contribution (-mu*N).
- @ref calculation must be 'relax'.
- @ref assume_isolated = 'esm' and @ref esm_bc = 'bc2' or 'bc3' must be set
in @ref SYSTEM namelist.
}
}
var gate -type LOGICAL {
default { .FALSE. }
see { zgate, relaxz, block, block_1, block_2, block_height }
info {
In the case of charged cells (@ref tot_charge .ne. 0) setting gate = .TRUE.
represents the counter charge (i.e. -tot_charge) not by a homogeneous
background charge but with a charged plate, which is placed at @ref zgate
(see below). Details of the gate potential can be found in
T. Brumme, M. Calandra, F. Mauri; PRB 89, 245406 (2014).
Note, that in systems which are not symmetric with respect to the plate,
one needs to enable the dipole correction! (@ref dipfield=.true.).
Currently, symmetry can be used with gate=.true. but carefully check
that no symmetry is included which maps @i z to -@i z even if in principle one
could still use them for symmetric systems (i.e. no dipole correction).
For @ref nosym=.false. verbosity is set to 'high'.
Note: this option was called "monopole" in v6.0 and 6.1 of pw.x
}
}
}
#
# NAMELIST &SYSTEM
#
namelist SYSTEM {
var ibrav -type INTEGER {
status { REQUIRED }
info {
Bravais-lattice index. Optional only if space_group is set.
If ibrav /= 0, specify EITHER [ @ref celldm(1)-@ref celldm(6) ]
OR [ @ref A, @ref B, @ref C, @ref cosAB, @ref cosAC, @ref cosBC ]
but NOT both. The lattice parameter "alat" is set to
alat = celldm(1) (in a.u.) or alat = A (in Angstrom);
see below for the other parameters.
For ibrav=0 specify the lattice vectors in @ref CELL_PARAMETERS,
optionally the lattice parameter alat = celldm(1) (in a.u.)
or = A (in Angstrom). If not specified, the lattice parameter is
taken from @ref CELL_PARAMETERS
IMPORTANT NOTICE 1:
with ibrav=0 lattice vectors must be given with a sufficiently large
number of digits and with the correct symmetry, or else symmetry
detection may fail and strange problems may arise in symmetrization.
IMPORTANT NOTICE 2:
do not use celldm(1) or A as a.u. to Ang conversion factor,
use the true lattice parameters or nothing,
specify units in @ref CELL_PARAMETERS and @ref ATOMIC_POSITIONS
ibrav structure celldm(2)-celldm(6)
or: b,c,cosbc,cosac,cosab
0 free
crystal axis provided in input: see card @ref CELL_PARAMETERS
1 cubic P (sc)
v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,1)
2 cubic F (fcc)
v1 = (a/2)(-1,0,1), v2 = (a/2)(0,1,1), v3 = (a/2)(-1,1,0)
3 cubic I (bcc)
v1 = (a/2)(1,1,1), v2 = (a/2)(-1,1,1), v3 = (a/2)(-1,-1,1)
-3 cubic I (bcc), more symmetric axis:
v1 = (a/2)(-1,1,1), v2 = (a/2)(1,-1,1), v3 = (a/2)(1,1,-1)
4 Hexagonal and Trigonal P celldm(3)=c/a
v1 = a(1,0,0), v2 = a(-1/2,sqrt(3)/2,0), v3 = a(0,0,c/a)
5 Trigonal R, 3fold axis c celldm(4)=cos(gamma)
The crystallographic vectors form a three-fold star around
the z-axis, the primitive cell is a simple rhombohedron:
v1 = a(tx,-ty,tz), v2 = a(0,2ty,tz), v3 = a(-tx,-ty,tz)
where c=cos(gamma) is the cosine of the angle gamma between
any pair of crystallographic vectors, tx, ty, tz are:
tx=sqrt((1-c)/2), ty=sqrt((1-c)/6), tz=sqrt((1+2c)/3)
-5 Trigonal R, 3fold axis <111> celldm(4)=cos(gamma)
The crystallographic vectors form a three-fold star around
<111>. Defining a' = a/sqrt(3) :
v1 = a' (u,v,v), v2 = a' (v,u,v), v3 = a' (v,v,u)
where u and v are defined as
u = tz - 2*sqrt(2)*ty, v = tz + sqrt(2)*ty
and tx, ty, tz as for case ibrav=5
Note: if you prefer x,y,z as axis in the cubic limit,
set u = tz + 2*sqrt(2)*ty, v = tz - sqrt(2)*ty
See also the note in Modules/latgen.f90
6 Tetragonal P (st) celldm(3)=c/a
v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,c/a)
7 Tetragonal I (bct) celldm(3)=c/a
v1=(a/2)(1,-1,c/a), v2=(a/2)(1,1,c/a), v3=(a/2)(-1,-1,c/a)
8 Orthorhombic P celldm(2)=b/a
celldm(3)=c/a
v1 = (a,0,0), v2 = (0,b,0), v3 = (0,0,c)
9 Orthorhombic base-centered(bco) celldm(2)=b/a
celldm(3)=c/a
v1 = (a/2, b/2,0), v2 = (-a/2,b/2,0), v3 = (0,0,c)
-9 as 9, alternate description
v1 = (a/2,-b/2,0), v2 = (a/2, b/2,0), v3 = (0,0,c)
91 Orthorhombic one-face base-centered A-type
celldm(2)=b/a
celldm(3)=c/a
v1 = (a, 0, 0), v2 = (0,b/2,-c/2), v3 = (0,b/2,c/2)
10 Orthorhombic face-centered celldm(2)=b/a
celldm(3)=c/a
v1 = (a/2,0,c/2), v2 = (a/2,b/2,0), v3 = (0,b/2,c/2)
11 Orthorhombic body-centered celldm(2)=b/a
celldm(3)=c/a
v1=(a/2,b/2,c/2), v2=(-a/2,b/2,c/2), v3=(-a/2,-b/2,c/2)
12 Monoclinic P, unique axis c celldm(2)=b/a
celldm(3)=c/a,
celldm(4)=cos(ab)
v1=(a,0,0), v2=(b*cos(gamma),b*sin(gamma),0), v3 = (0,0,c)
where gamma is the angle between axis a and b.
-12 Monoclinic P, unique axis b celldm(2)=b/a
celldm(3)=c/a,
celldm(5)=cos(ac)
v1 = (a,0,0), v2 = (0,b,0), v3 = (c*cos(beta),0,c*sin(beta))
where beta is the angle between axis a and c
13 Monoclinic base-centered celldm(2)=b/a
(unique axis c) celldm(3)=c/a,
celldm(4)=cos(gamma)
v1 = ( a/2, 0, -c/2),
v2 = (b*cos(gamma), b*sin(gamma), 0 ),
v3 = ( a/2, 0, c/2),
where gamma=angle between axis a and b projected on xy plane
-13 Monoclinic base-centered celldm(2)=b/a
(unique axis b) celldm(3)=c/a,
celldm(5)=cos(beta)
v1 = ( a/2, b/2, 0),
v2 = ( -a/2, b/2, 0),
v3 = (c*cos(beta), 0, c*sin(beta)),
where beta=angle between axis a and c projected on xz plane
IMPORTANT NOTICE: until QE v.6.4.1, axis for ibrav=-13 had a
different definition: v1(old) = v2(now), v2(old) = -v1(now)
14 Triclinic celldm(2)= b/a,
celldm(3)= c/a,
celldm(4)= cos(bc),
celldm(5)= cos(ac),
celldm(6)= cos(ab)
v1 = (a, 0, 0),
v2 = (b*cos(gamma), b*sin(gamma), 0)
v3 = (c*cos(beta), c*(cos(alpha)-cos(beta)cos(gamma))/sin(gamma),
c*sqrt( 1 + 2*cos(alpha)cos(beta)cos(gamma)
- cos(alpha)^2-cos(beta)^2-cos(gamma)^2 )/sin(gamma) )
where alpha is the angle between axis b and c
beta is the angle between axis a and c
gamma is the angle between axis a and b
}
}
group {
label { Either: }
dimension celldm -start 1 -end 6 -type REAL {
see { ibrav }
info {
Crystallographic constants - see the @ref ibrav variable.
Specify either these OR @ref A,@ref B,@ref C,@ref cosAB,@ref cosBC,@ref cosAC NOT both.
Only needed values (depending on "ibrav") must be specified
alat = @ref celldm(1) is the lattice parameter "a" (in BOHR)
If @ref ibrav==0, only @ref celldm(1) is used if present;
cell vectors are read from card @ref CELL_PARAMETERS
}
}
label { Or: }
vargroup -type REAL {
var A
var B
var C
var cosAB
var cosAC
var cosBC
see { ibrav }
info {
Traditional crystallographic constants:
a,b,c in ANGSTROM
cosAB = cosine of the angle between axis a and b (gamma)
cosAC = cosine of the angle between axis a and c (beta)
cosBC = cosine of the angle between axis b and c (alpha)
The axis are chosen according to the value of @ref ibrav.
Specify either these OR @ref celldm but NOT both.
Only needed values (depending on @ref ibrav) must be specified.
The lattice parameter alat = A (in ANGSTROM ).
If @ref ibrav == 0, only A is used if present, and
cell vectors are read from card @ref CELL_PARAMETERS.
}
}
}
var nat -type INTEGER {
status { REQUIRED }
info {
number of atoms in the unit cell (ALL atoms, except if
space_group is set, in which case, INEQUIVALENT atoms)
}
}
var ntyp -type INTEGER {
status { REQUIRED }
info {
number of types of atoms in the unit cell
}
}
var nbnd -type INTEGER {
default {
for an insulator, @ref nbnd = number of valence bands
(@ref nbnd = # of electrons /2);
@br for a metal, 20% more (minimum 4 more)
}
info {
Number of electronic states (bands) to be calculated.
Note that in spin-polarized calculations the number of
k-point, not the number of bands per k-point, is doubled
}
}
var tot_charge -type REAL {
default { 0.0 }
info {
Total charge of the system. Useful for simulations with charged cells.
By default the unit cell is assumed to be neutral (tot_charge=0).
tot_charge=+1 means one electron missing from the system,
tot_charge=-1 means one additional electron, and so on.
In a periodic calculation a compensating jellium background is
inserted to remove divergences if the cell is not neutral.
}
}
dimension starting_charge -start 1 -end ntyp -type REAL {
default { 0.0 }
info {
starting charge on atomic type 'i',
to create starting potential with @ref startingpot = 'atomic'.
}
}
var tot_magnetization -type REAL {
default { -1 [unspecified] }
info {
Total majority spin charge - minority spin charge.
Used to impose a specific total electronic magnetization.
If unspecified then tot_magnetization variable is ignored and
the amount of electronic magnetization is determined during
the self-consistent cycle.
}
}
dimension starting_magnetization -start 1 -end ntyp -type REAL {
info {
Starting spin polarization on atomic type 'i' in a spin
polarized calculation. Values range between -1 (all spins
down for the valence electrons of atom type 'i') to 1
(all spins up). Breaks the symmetry and provides a starting
point for self-consistency. The default value is zero, BUT a
value MUST be specified for AT LEAST one atomic type in spin
polarized calculations, unless you constrain the magnetization
(see @ref tot_magnetization and @ref constrained_magnetization).
Note that if you start from zero initial magnetization, you
will invariably end up in a nonmagnetic (zero magnetization)
state. If you want to start from an antiferromagnetic state,
you may need to define two different atomic species
corresponding to sublattices of the same atomic type.
starting_magnetization is ignored if you are performing a
non-scf calculation, if you are restarting from a previous
run, or restarting from an interrupted run.
If you fix the magnetization with @ref tot_magnetization,
you should not specify starting_magnetization.
In the spin-orbit case starting with zero
starting_magnetization on all atoms imposes time reversal
symmetry. The magnetization is never calculated and
kept zero (the internal variable domag is .FALSE.).
}
}
var ecutwfc -type REAL {
status { REQUIRED }
info {
kinetic energy cutoff (Ry) for wavefunctions
}
}
var ecutrho -type REAL {
default { 4 * @ref ecutwfc }
info {
Kinetic energy cutoff (Ry) for charge density and potential
For norm-conserving pseudopotential you should stick to the
default value, you can reduce it by a little but it will
introduce noise especially on forces and stress.
If there are ultrasoft PP, a larger value than the default is
often desirable (ecutrho = 8 to 12 times @ref ecutwfc, typically).
PAW datasets can often be used at 4*@ref ecutwfc, but it depends
on the shape of augmentation charge: testing is mandatory.
The use of gradient-corrected functional, especially in cells
with vacuum, or for pseudopotential without non-linear core
correction, usually requires an higher values of ecutrho
to be accurately converged.
}
}
var ecutfock -type REAL {
default { ecutrho }
info {
Kinetic energy cutoff (Ry) for the exact exchange operator in
EXX type calculations. By default this is the same as @ref ecutrho
but in some EXX calculations, a significant speed-up can be obtained
by reducing ecutfock, at the expense of some loss in accuracy.
Must be .gt. @ref ecutwfc. Not implemented for stress calculation
and for US-PP and PAW pseudopotentials.
Use with care, especially in metals where it may give raise
to instabilities.
}
}
vargroup -type INTEGER {
var nr1
var nr2
var nr3
info {
Three-dimensional FFT mesh (hard grid) for charge
density (and scf potential). If not specified
the grid is calculated based on the cutoff for
charge density (see also @ref ecutrho)
Note: you must specify all three dimensions for this setting to
be used.
}
}
vargroup -type INTEGER {
var nr1s
var nr2s
var nr3s
info {
Three-dimensional mesh for wavefunction FFT and for the smooth
part of charge density ( smooth grid ).
Coincides with @ref nr1, @ref nr2, @ref nr3 if @ref ecutrho = 4 * ecutwfc ( default )
Note: you must specify all three dimensions for this setting to
be used.
}
}
var nosym -type LOGICAL {
default { .FALSE. }
info {
if (.TRUE.) symmetry is not used. Consequences:
- if a list of k points is provided in input, it is used
"as is": symmetry-inequivalent k-points are not generated,
and the charge density is not symmetrized;
- if a uniform (Monkhorst-Pack) k-point grid is provided in
input, it is expanded to cover the entire Brillouin Zone,
irrespective of the crystal symmetry.
Time reversal symmetry is assumed so k and -k are considered
as equivalent unless @ref noinv=.true. is specified.
Do not use this option unless you know exactly what you want
and what you get. May be useful in the following cases:
- in low-symmetry large cells, if you cannot afford a k-point
grid with the correct symmetry
- in MD simulations
- in calculations for isolated atoms
}
}
var nosym_evc -type LOGICAL {
default { .FALSE. }
info {
if (.TRUE.) symmetry is not used, and k points are
forced to have the symmetry of the Bravais lattice;
an automatically generated Monkhorst-Pack grid will contain
all points of the grid over the entire Brillouin Zone,
plus the points rotated by the symmetries of the Bravais
lattice which were not in the original grid. The same
applies if a k-point list is provided in input instead
of a Monkhorst-Pack grid. Time reversal symmetry is assumed
so k and -k are equivalent unless @ref noinv=.true. is specified.
This option differs from @ref nosym because it forces k-points
in all cases to have the full symmetry of the Bravais lattice
(not all uniform grids have such property!)
}
}
var noinv -type LOGICAL {
default { .FALSE. }
info {
if (.TRUE.) disable the usage of k => -k symmetry
(time reversal) in k-point generation
}
}
var no_t_rev -type LOGICAL {
default { .FALSE. }
info {
if (.TRUE.) disable the usage of magnetic symmetry operations
that consist in a rotation + time reversal.
}
}
var force_symmorphic -type LOGICAL {
default { .FALSE. }
info {
if (.TRUE.) force the symmetry group to be symmorphic by disabling
symmetry operations having an associated fractionary translation
}
}
var use_all_frac -type LOGICAL {
default { .FALSE. }
info {
if (.FALSE.) force real-space FFT grids to be commensurate with
fractionary translations of non-symmorphic symmetry operations,
if present (e.g.: if a fractional translation (0,0,c/4) exists,
the FFT dimension along the c axis must be multiple of 4).
if (.TRUE.) do not impose any constraints to FFT grids, even in
the presence of non-symmorphic symmetry operations.
BEWARE: use_all_frac=.TRUE. may lead to wrong results for
hybrid functionals and phonon calculations. Both cases use
symmetrization in real space that works for non-symmorphic
operations only if the real-space FFT grids are commensurate.
}
}
var occupations -type CHARACTER {
options {
info { Available options are: }
opt -val 'smearing' {
gaussian smearing for metals;
see variables @ref smearing and @ref degauss
}
opt -val 'tetrahedra' {
Tetrahedron method, Bloechl's version:
P.E. Bloechl, PRB 49, 16223 (1994)
Requires uniform grid of k-points, to be
automatically generated (see card @ref K_POINTS).
Well suited for calculation of DOS,
less so (because not variational) for
force/optimization/dynamics calculations.
}
opt -val 'tetrahedra_lin' {
Original linear tetrahedron method.
To be used only as a reference;
the optimized tetrahedron method is more efficient.
}
opt -val 'tetrahedra_opt' {
Optimized tetrahedron method:
see M. Kawamura, PRB 89, 094515 (2014).
Can be used for phonon calculations as well.
}
opt -val 'fixed' {
for insulators with a gap
}
opt -val 'from_input' {
The occupation are read from input file,
card @ref OCCUPATIONS. Option valid only for a
single k-point, requires @ref nbnd to be set
in input. Occupations should be consistent
with the value of @ref tot_charge.
}
}
}
var one_atom_occupations -type LOGICAL {
default { .FALSE. }
info {
This flag is used for isolated atoms (@ref nat=1) together with
@ref occupations='from_input'. If it is .TRUE., the wavefunctions
are ordered as the atomic starting wavefunctions, independently
from their eigenvalue. The occupations indicate which atomic
states are filled.
The order of the states is written inside the UPF pseudopotential file.
In the scalar relativistic case:
S -> l=0, m=0
P -> l=1, z, x, y
D -> l=2, r^2-3z^2, xz, yz, xy, x^2-y^2
In the noncollinear magnetic case (with or without spin-orbit),
each group of states is doubled. For instance:
P -> l=1, z, x, y for spin up, l=1, z, x, y for spin down.
Up and down is relative to the direction of the starting
magnetization.
In the case with spin-orbit and time-reversal
(@ref starting_magnetization=0.0) the atomic wavefunctions are
radial functions multiplied by spin-angle functions.
For instance:
P -> l=1, j=1/2, m_j=-1/2,1/2. l=1, j=3/2,
m_j=-3/2, -1/2, 1/2, 3/2.
In the magnetic case with spin-orbit the atomic wavefunctions
can be forced to be spin-angle functions by setting
@ref starting_spin_angle to .TRUE..
}
}
var starting_spin_angle -type LOGICAL {
default { .FALSE. }
info {
In the spin-orbit case when @ref domag=.TRUE., by default,
the starting wavefunctions are initialized as in scalar
relativistic noncollinear case without spin-orbit.
By setting @ref starting_spin_angle=.TRUE. this behaviour can
be changed and the initial wavefunctions are radial
functions multiplied by spin-angle functions.
When @ref domag=.FALSE. the initial wavefunctions are always
radial functions multiplied by spin-angle functions
independently from this flag.
When @ref lspinorb is .FALSE. this flag is not used.
}
}
var degauss -type REAL {
default { 0.D0 Ry }
info {
value of the gaussian spreading (Ry) for brillouin-zone
integration in metals.
}
}
var smearing -type CHARACTER {
default { 'gaussian' }
options {
info {
Available options are:
}
opt -val {'gaussian', 'gauss'} {
ordinary Gaussian spreading (Default)
}
opt -val {'methfessel-paxton', 'm-p', 'mp'} {
Methfessel-Paxton first-order spreading
(see PRB 40, 3616 (1989)).
}
opt -val {'marzari-vanderbilt', 'cold', 'm-v', 'mv'} {
Marzari-Vanderbilt-DeVita-Payne cold smearing
(see PRL 82, 3296 (1999))
}
opt -val {'fermi-dirac', 'f-d', 'fd'} {
smearing with Fermi-Dirac function
}
}
}
var nspin -type INTEGER {
default { 1 }
info {
nspin = 1 : non-polarized calculation (default)
nspin = 2 : spin-polarized calculation, LSDA
(magnetization along z axis)
nspin = 4 : spin-polarized calculation, noncollinear
(magnetization in generic direction)
DO NOT specify @ref nspin in this case;
specify @ref noncolin=.TRUE. instead
}
}
var noncolin -type LOGICAL {
default { .false. }
info {
if .true. the program will perform a noncollinear calculation.
}
}
var ecfixed -type REAL { default { 0.0 }; see { q2sigma } }
var qcutz -type REAL { default { 0.0 }; see { q2sigma } }
var q2sigma -type REAL {
default { 0.1 }
info {
ecfixed, qcutz, q2sigma: parameters for modified functional to be
used in variable-cell molecular dynamics (or in stress calculation).
"ecfixed" is the value (in Rydberg) of the constant-cutoff;
"qcutz" and "q2sigma" are the height and the width (in Rydberg)
of the energy step for reciprocal vectors whose square modulus
is greater than "ecfixed". In the kinetic energy, G^2 is
replaced by G^2 + qcutz * (1 + erf ( (G^2 - ecfixed)/q2sigma) )
See: M. Bernasconi et al, J. Phys. Chem. Solids 56, 501 (1995),
doi:10.1016/0022-3697(94)00228-2
}
}
var input_dft -type CHARACTER {
default { read from pseudopotential files }
info {
Exchange-correlation functional: eg 'PBE', 'BLYP' etc
See Modules/funct.f90 for allowed values.
Overrides the value read from pseudopotential files.
Use with care and if you know what you are doing!
}
}
var exx_fraction -type REAL {
default { it depends on the specified functional }
info {
Fraction of EXX for hybrid functional calculations. In the case of
@ref input_dft='PBE0', the default value is 0.25, while for @ref input_dft='B3LYP'
the @ref exx_fraction default value is 0.20.
}
}
var screening_parameter -type REAL {
default {0.106}
info {
screening_parameter for HSE like hybrid functionals.
For more information, see:
J. Chem. Phys. 118, 8207 (2003), doi:10.1063/1.1564060
J. Chem. Phys. 124, 219906 (2006), doi:10.1063/1.2204597
}
}
var exxdiv_treatment -type CHARACTER {
default {'gygi-baldereschi'}
options {
info {
Specific for EXX. It selects the kind of approach to be used
for treating the Coulomb potential divergencies at small q vectors.
}
opt -val 'gygi-baldereschi' { appropriate for cubic and quasi-cubic supercells }
opt -val 'vcut_spherical' { appropriate for cubic and quasi-cubic supercells }
opt -val 'vcut_ws' { appropriate for strongly anisotropic supercells, see also @ref ecutvcut. }
opt -val 'none' { sets Coulomb potential at G,q=0 to 0.0 (required for GAU-PBE) }
}
}
var x_gamma_extrapolation -type LOGICAL {
default {.true.}
info {
Specific for EXX. If .true., extrapolate the G=0 term of the
potential (see README in examples/EXX_example for more)
Set this to .false. for GAU-PBE.
}
}
var ecutvcut -type REAL {
default { 0.0 Ry }
see { exxdiv_treatment }
info {
Reciprocal space cutoff for correcting Coulomb potential
divergencies at small q vectors.
}
}
vargroup -type INTEGER {
var nqx1
var nqx2
var nqx3
info {
Three-dimensional mesh for q (k1-k2) sampling of
the Fock operator (EXX). Can be smaller than
the number of k-points.
Currently this defaults to the size of the k-point mesh used.
In QE =< 5.0.2 it defaulted to nqx1=nqx2=nqx3=1.
}
}
var localization_thr -type REAL {
default {0.0 }
info {
Overlap threshold over which the exchange integral over a pair of localized orbitals
is included in the evaluation of EXX operator. Any value greater than 0.0 triggers
the SCDM localization and the evaluation on EXX using the localized orbitals.
Very small value of the threshold should yield the same result as the default EXX
evaluation }
}
var lda_plus_u -type LOGICAL {
default { .FALSE. }
status {
DFT+U (formerly known as LDA+U) currently works only for
a few selected elements. Modify @tt Modules/set_hubbard_l.f90 and
@tt PW/src/tabd.f90 if you plan to use DFT+U with an element that
is not configured there.
}
info {
Specify @ref lda_plus_u = .TRUE. to enable DFT+U calculations
See: Anisimov, Zaanen, and Andersen, PRB 44, 943 (1991);
Anisimov et al., PRB 48, 16929 (1993);
Liechtenstein, Anisimov, and Zaanen, PRB 52, R5467 (1994).
You must specify, for each species with a U term, the value of
U and (optionally) alpha, J of the Hubbard model (all in eV):
see @ref lda_plus_u_kind, @ref Hubbard_U, @ref Hubbard_alpha, @ref Hubbard_J
}
}
var lda_plus_u_kind -type INTEGER {
default { 0 }
info {
Specifies the type of DFT+U calculation:
0 simplified version of Cococcioni and de Gironcoli,
PRB 71, 035105 (2005), using @ref Hubbard_U
1 rotationally invariant scheme of Liechtenstein et al.,
using @ref Hubbard_U and @ref Hubbard_J
}
}
dimension Hubbard_U -start 1 -end ntyp -type REAL {
default { 0.D0 for all species }
info {
Hubbard_U(i): U parameter (eV) for species i, DFT+U calculation
}
}
dimension Hubbard_J0 -start 1 -end ntype -type REAL {
default { 0.D0 for all species }
info {
Hubbard_J0(i): J0 parameter (eV) for species i, DFT+U+J calculation,
see PRB 84, 115108 (2011) for details.
}
}
dimension Hubbard_alpha -start 1 -end ntyp -type REAL {
default { 0.D0 for all species }
info {
Hubbard_alpha(i) is the perturbation (on atom i, in eV)
used to compute U with the linear-response method of
Cococcioni and de Gironcoli, PRB 71, 035105 (2005)
(only for @ref lda_plus_u_kind=0)
}
}
dimension Hubbard_beta -start 1 -end ntyp -type REAL {
default { 0.D0 for all species }
info {
Hubbard_beta(i) is the perturbation (on atom i, in eV)
used to compute J0 with the linear-response method of
Cococcioni and de Gironcoli, PRB 71, 035105 (2005)
(only for @ref lda_plus_u_kind=0). See also
PRB 84, 115108 (2011).
}
}
multidimension Hubbard_J -start 1,1 -end 3,ntyp -indexes i,ityp -type REAL {
default { 0.D0 for all species }
info {
Hubbard_J(i,ityp): J parameters (eV) for species ityp,
used in DFT+U calculations (only for @ref lda_plus_u_kind=1)
For p orbitals: J = Hubbard_J(1,ityp);
For d orbitals: J = Hubbard_J(1,ityp), B = Hubbard_J(2,ityp);
For f orbitals: J = Hubbard_J(1,ityp), E2 = Hubbard_J(2,ityp),
E3= Hubbard_J(3,ityp).
If B or E2 or E3 are not specified or set to 0 they will be
calculated from J using atomic ratios.
}
}
multidimension starting_ns_eigenvalue -indexes m,ispin,ityp -start 1,1,1 -end 2*lmax+1,nspin\ or\ npol,ntyp -type REAL {
default { -1.d0 that means NOT SET }
info {
In the first iteration of an DFT+U run it overwrites
the m-th eigenvalue of the ns occupation matrix for the
ispin component of atomic species ityp.
For the noncolin case the ispin index runs up to npol.
The value lmax is given by the maximum angular momentum
number to which the Hubbard U is applied.
Leave unchanged eigenvalues that are not set.
This is useful to suggest the desired orbital occupations
when the default choice takes another path.
}
}
var U_projection_type -type CHARACTER {
default { 'atomic' }
options {
info {
Only active when @ref lda_plus_U is .true., specifies the type
of projector on localized orbital to be used in the DFT+U
scheme.
Currently available choices:
}
opt -val 'atomic' { use atomic wfc's (as they are) to build the projector }
opt -val 'ortho-atomic' { use Lowdin orthogonalized atomic wfc's }
opt -val 'norm-atomic' {
Lowdin normalization of atomic wfc. Keep in mind:
atomic wfc are not orthogonalized in this case.
This is a "quick and dirty" trick to be used when
atomic wfc from the pseudopotential are not
normalized (and thus produce occupation whose
value exceeds unity). If orthogonalized wfc are
not needed always try @b 'atomic' first.
}
opt -val 'file' {
use the information from file "prefix".atwfc that must
have been generated previously, for instance by pmw.x
(see PP/src/poormanwannier.f90 for details).
}
opt -val 'pseudo' {
use the pseudopotential projectors. The charge density
outside the atomic core radii is excluded.
N.B.: for atoms with +U, a pseudopotential with the
all-electron atomic wavefunctions is required (i.e.,
as generated by ld1.x with lsave_wfc flag).
}
info {
NB: forces and stress currently implemented only for the
'atomic' and 'pseudo' choice.
}
}
}
var ensemble_energies -type LOGICAL {
default { .false. }
info {
If ensemble_energies = .true., an ensemble of xc energies
is calculated non-selfconsistently for perturbed
exchange-enhancement factors and LDA vs. PBE correlation
ratios after each converged electronic ground state
calculation.
Ensemble energies can be analyzed with the 'bee' utility
included with libbeef.
Requires linking against libbeef.
input_dft must be set to a BEEF-type functional
(e.g. input_dft = 'BEEF-vdW')
}
}
var edir -type INTEGER {
info {
The direction of the electric field or dipole correction is
parallel to the bg(:,edir) reciprocal lattice vector, so the
potential is constant in planes defined by FFT grid points;
@ref edir = 1, 2 or 3. Used only if @ref tefield is .TRUE.
}
}
var emaxpos -type REAL {
default { 0.5D0 }
info {
Position of the maximum of the saw-like potential along crystal
axis @ref edir, within the unit cell (see below), 0 < emaxpos < 1
Used only if @ref tefield is .TRUE.
}
}
var eopreg -type REAL {
default { 0.1D0 }
info {
Zone in the unit cell where the saw-like potential decreases.
( see below, 0 < eopreg < 1 ). Used only if @ref tefield is .TRUE.
}
}
var eamp -type REAL {
default { 0.001 a.u. }
info {
Amplitude of the electric field, in ***Hartree*** a.u.;
1 a.u. = 51.4220632*10^10 V/m. Used only if @ref tefield==.TRUE.
The saw-like potential increases with slope @ref eamp in the
region from (@ref emaxpos+@ref eopreg-1) to (@ref emaxpos), then decreases
to 0 until (@ref emaxpos+@ref eopreg), in units of the crystal
vector @ref edir. Important: the change of slope of this
potential must be located in the empty region, or else
unphysical forces will result.
}
}
dimension angle1 -start 1 -end ntyp -type REAL {
info {
The angle expressed in degrees between the initial
magnetization and the z-axis. For noncollinear calculations
only; index i runs over the atom types.
}
}
dimension angle2 -start 1 -end ntyp -type REAL {
info {
The angle expressed in degrees between the projection
of the initial magnetization on x-y plane and the x-axis.
For noncollinear calculations only.
}
}
var lforcet -type LOGICAL {
info {
When starting a non collinear calculation using an existing density
file from a collinear lsda calculation assumes previous density points in
@i z direction and rotates it in the direction described by @ref angle1 and
@ref angle2 variables for atomic type 1
}
}
var constrained_magnetization -type CHARACTER {
see { lambda, fixed_magnetization }
default { 'none' }
options {
info {
Used to perform constrained calculations in magnetic systems.
Currently available choices:
}
opt -val 'none' {
no constraint
}
opt -val 'total' {
total magnetization is constrained by
adding a penalty functional to the total energy:
LAMBDA * SUM_{i} ( magnetization(i) - fixed_magnetization(i) )**2
where the sum over i runs over the three components of
the magnetization. Lambda is a real number (see below).
Noncolinear case only. Use @ref tot_magnetization for LSDA
}
opt -val 'atomic' {
atomic magnetization are constrained to the defined
starting magnetization adding a penalty:
LAMBDA * SUM_{i,itype} ( magnetic_moment(i,itype) - mcons(i,itype) )**2
where i runs over the cartesian components (or just z
in the collinear case) and itype over the types (1-ntype).
mcons(:,:) array is defined from starting_magnetization,
(and angle1, angle2 in the non-collinear case). lambda is
a real number
}
opt -val {'total direction'} {
the angle theta of the total magnetization
with the z axis (theta = fixed_magnetization(3))
is constrained:
LAMBDA * ( arccos(magnetization(3)/mag_tot) - theta )**2
where mag_tot is the modulus of the total magnetization.
}
opt -val {'atomic direction'} {
not all the components of the atomic
magnetic moment are constrained but only the cosine
of angle1, and the penalty functional is:
LAMBDA * SUM_{itype} ( mag_mom(3,itype)/mag_mom_tot - cos(angle1(ityp)) )**2
}
info {
N.B.: symmetrization may prevent to reach the desired orientation
of the magnetization. Try not to start with very highly symmetric
configurations or use the nosym flag (only as a last remedy)
}
}
}
dimension fixed_magnetization -start 1 -end 3 -type REAL {
see { constrained_magnetization }
default { 0.d0 }
info {
total magnetization vector (x,y,z components) to be kept
fixed when @ref constrained_magnetization=='total'
}
}
var lambda -type REAL {
see { constrained_magnetization }
default { 1.d0 }
info {
parameter used for constrained_magnetization calculations
N.B.: if the scf calculation does not converge, try to reduce lambda
to obtain convergence, then restart the run with a larger lambda
}
}
var report -type INTEGER {
default { -1 }
info {
determines when atomic magnetic moments are printed on output:
report = 0 never
report =-1 at the beginning of the scf and at convergence
report = N: as -1, plus every N scf iterations
}
}
var lspinorb -type LOGICAL {
info {
if .TRUE. the noncollinear code can use a pseudopotential with
spin-orbit.
}
}
var assume_isolated -type CHARACTER {
default { 'none' }
options {
info {
Used to perform calculation assuming the system to be
isolated (a molecule or a cluster in a 3D supercell).
Currently available choices:
}
opt -val 'none' {
(default): regular periodic calculation w/o any correction.
}
opt -val {'makov-payne', 'm-p', 'mp'} {
the Makov-Payne correction to the
total energy is computed. An estimate of the vacuum
level is also calculated so that eigenvalues can be
properly aligned. ONLY FOR CUBIC SYSTEMS (@ref ibrav=1,2,3).
Theory: G.Makov, and M.C.Payne,
"Periodic boundary conditions in ab initio
calculations" , PRB 51, 4014 (1995).
}
opt -val {'martyna-tuckerman', 'm-t', 'mt'} {
Martyna-Tuckerman correction
to both total energy and scf potential. Adapted from:
G.J. Martyna, and M.E. Tuckerman,
"A reciprocal space based method for treating long
range interactions in ab-initio and force-field-based
calculation in clusters", J. Chem. Phys. 110, 2810 (1999),
doi:10.1063/1.477923.
}
opt -val 'esm' {
Effective Screening Medium Method.
For polarized or charged slab calculation, embeds
the simulation cell within an effective semi-
infinite medium in the perpendicular direction
(along z). Embedding regions can be vacuum or
semi-infinite metal electrodes (use @ref esm_bc to
choose boundary conditions). If between two
electrodes, an optional electric field
('esm_efield') may be applied. Method described in
M. Otani and O. Sugino, "First-principles calculations
of charged surfaces and interfaces: A plane-wave
nonrepeated slab approach", PRB 73, 115407 (2006).
NB:
- Two dimensional (xy plane) average charge density
and electrostatic potentials are printed out to
'prefix.esm1'.
- Requires cell with a_3 lattice vector along z,
normal to the xy plane, with the slab centered
around z=0. Also requires symmetry checking to be
disabled along z, either by setting @ref nosym = .TRUE.
or by very slight displacement (i.e., 5e-4 a.u.)
of the slab along z.
- Components of the total stress; sigma_xy, sigma_yz,
sigma_zz, sigma_zy, and sigma_zx are meaningless
because ESM stress routines calculate only
components of stress; sigma_xx, sigma_xy, sigma_yx,
and sigma_yy.
- In case of calculation='vc-relax', use
cell_dofree='2Dxy' or other parameters so that
c-vector along z-axis should not be moved.
See @ref esm_bc, @ref esm_efield, @ref esm_w, @ref esm_nfit.
}
opt -val '2D' {
Truncation of the Coulomb interaction in the z direction
for structures periodic in the x-y plane. Total energy,
forces and stresses are computed in a two-dimensional framework.
Linear-response calculations () done on top of a self-consistent
calculation with this flag will automatically be performed in
the 2D framework as well. Please refer to:
Sohier, T., Calandra, M., & Mauri, F. (2017), Density functional
perturbation theory for gated two-dimensional heterostructures:
Theoretical developments and application to flexural phonons in graphene.
Physical Review B, 96(7), 75448. https://doi.org/10.1103/PhysRevB.96.075448
NB:
- The length of the unit-cell along the z direction should
be larger than twice the thickness of the 2D material
(including electrons). A reasonable estimate for a
layer's thickness could be the interlayer distance in the
corresponding layered bulk material. Otherwise,
the atomic thickness + 10 bohr should be a safe estimate.
There is also a lower limit of 20 bohr imposed by the cutoff
radius used to read pseudopotentials (see read_pseudo.f90 in Modules).
- As for ESM above, only in-plane stresses make sense and one
should use cell_dofree='2Dxy' in a vc-relax calculation.
}
}
}
var esm_bc -type CHARACTER {
see { assume_isolated }
default { 'pbc' }
options {
info {
If @ref assume_isolated = 'esm', determines the boundary
conditions used for either side of the slab.
Currently available choices:
}
opt -val 'pbc' { (default): regular periodic calculation (no ESM). }
opt -val 'bc1' { Vacuum-slab-vacuum (open boundary conditions). }
opt -val 'bc2' {
Metal-slab-metal (dual electrode configuration).
See also @ref esm_efield.
}
opt -val 'bc3' { Vacuum-slab-metal }
}
}
var esm_w -type REAL {
see { assume_isolated }
default { 0.d0 }
info {
If @ref assume_isolated = 'esm', determines the position offset
[in a.u.] of the start of the effective screening region,
measured relative to the cell edge. (ESM region begins at
z = +/- [L_z/2 + esm_w] ).
}
}
var esm_efield -type REAL {
see { assume_isolated }
default { 0.d0 }
info {
If @ref assume_isolated = 'esm' and @ref esm_bc = 'bc2', gives the
magnitude of the electric field [Ry/a.u.] to be applied
between semi-infinite ESM electrodes.
}
}
var esm_nfit -type INTEGER {
see { assume_isolated }
default { 4 }
info {
If @ref assume_isolated = 'esm', gives the number of z-grid points
for the polynomial fit along the cell edge.
}
}
var fcp_mu -type REAL {
see { lfcpopt }
default { 0.d0 }
info {
If @ref lfcpopt = .TRUE., gives the target Fermi energy [Ry]. One can start
with appropriate total charge of the system by giving 'tot_charge'.
}
}
var vdw_corr -type CHARACTER {
default { 'none' }
see {
london_s6, london_rcut, london_c6, london_rvdw,
dftd3_version, dftd3_threebody, ts_vdw_econv_thr, ts_vdw_isolated, xdm_a1, xdm_a2
}
options {
info {
Type of Van der Waals correction. Allowed values:
}
opt -val {'grimme-d2', 'Grimme-D2', 'DFT-D', 'dft-d'} {
Semiempirical Grimme's DFT-D2. Optional variables:
@ref london_s6, @ref london_rcut, @ref london_c6, @ref london_rvdw
S. Grimme, J. Comp. Chem. 27, 1787 (2006), doi:10.1002/jcc.20495
V. Barone et al., J. Comp. Chem. 30, 934 (2009), doi:10.1002/jcc.21112
}
opt -val {'grimme-d3', 'Grimme-D3', 'DFT-D3', 'dft-d3' } {
Semiempirical Grimme's DFT-D3. Optional variables:
@ref dftd3_version, @ref dftd3_threebody
S. Grimme et al, J. Chem. Phys 132, 154104 (2010), doi:10.1002/jcc.20495
}
opt -val {'TS', 'ts', 'ts-vdw', 'ts-vdW', 'tkatchenko-scheffler'} {
Tkatchenko-Scheffler dispersion corrections with first-principle derived
C6 coefficients.
Optional variables: @ref ts_vdw_econv_thr, @ref ts_vdw_isolated
See A. Tkatchenko and M. Scheffler, PRL 102, 073005 (2009).
}
opt -val {'XDM', 'xdm'} {
Exchange-hole dipole-moment model. Optional variables: @ref xdm_a1, @ref xdm_a2
A. D. Becke et al., J. Chem. Phys. 127, 154108 (2007), doi:10.1063/1.2795701
A. Otero de la Roza et al., J. Chem. Phys. 136, 174109 (2012),
doi:10.1063/1.4705760
}
info { Note that non-local functionals (eg vdw-DF) are NOT specified here but in @ref input_dft }
}
}
var london -type LOGICAL {
default { .FALSE. }
status {
OBSOLESCENT, same as @ref vdw_corr='DFT-D'
}
}
var london_s6 -type REAL {
default { 0.75 }
info {
global scaling parameter for DFT-D. Default is good for PBE.
}
}
dimension london_c6 -type REAL -start 1 -end ntyp {
default { standard Grimme-D2 values }
info {
atomic C6 coefficient of each atom type
( if not specified default values from S. Grimme, J. Comp. Chem. 27, 1787 (2006),
doi:10.1002/jcc.20495 are used; see file Modules/mm_dispersion.f90 )
}
}
dimension london_rvdw -type REAL -start 1 -end ntyp {
default { standard Grimme-D2 values }
info {
atomic vdw radii of each atom type
( if not specified default values from S. Grimme, J. Comp. Chem. 27, 1787 (2006),
doi:10.1002/jcc.20495 are used; see file Modules/mm_dispersion.f90 )
}
}
var london_rcut -type REAL {
default { 200 }
info {
cutoff radius (a.u.) for dispersion interactions
}
}
var dftd3_version -type integer {
default { 3 }
options {
info {
Version of Grimme implementation of Grimme-D3:
}
opt -val {dftd3_version = 2} {
Original Grimme-D2 parametrization
}
opt -val {dftd3_version = 3} {
Grimme-D3 (zero damping)
}
opt -val {dftd3_version = 4} {
Grimme-D3 (BJ damping)
}
opt -val {dftd3_version = 5} {
Grimme-D3M (zero damping)
}
opt -val {dftd3_version = 6} {
Grimme-D3M (BJ damping)
}
info {
NOTE: not all functionals are parametrized.
}
}
}
var dftd3_threebody -type LOGICAL {
default { TRUE }
info {
Turn three-body terms in Grimme-D3 on. If .false. two-body contributions
only are computed, using two-body parameters of Grimme-D3.
If dftd3_version=2, three-body contribution is always disabled.
}
}
var ts_vdw_econv_thr -type REAL {
default { 1.D-6 }
info {
Optional: controls the convergence of the vdW energy (and forces). The default value
is a safe choice, likely too safe, but you do not gain much in increasing it
}
}
var ts_vdw_isolated -type LOGICAL {
default { .FALSE. }
info {
Optional: set it to .TRUE. when computing the Tkatchenko-Scheffler vdW energy
for an isolated (non-periodic) system.
}
}
var xdm -type LOGICAL {
default { .FALSE. }
status {
OBSOLESCENT, same as @ref vdw_corr='xdm'
}
}
var xdm_a1 -type REAL {
default { 0.6836 }
info {
Damping function parameter a1 (adimensional). It is NOT necessary to give
a value if the functional is one of B86bPBE, PW86PBE, PBE, BLYP. For functionals
in this list, the coefficients are given in:
http://schooner.chem.dal.ca/wiki/XDM
A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 138, 204109 (2013),
doi:10.1063/1.4705760
}
}
var xdm_a2 -type REAL {
default { 1.5045 }
info {
Damping function parameter a2 (angstrom). It is NOT necessary to give
a value if the functional is one of B86bPBE, PW86PBE, PBE, BLYP. For functionals
in this list, the coefficients are given in:
http://schooner.chem.dal.ca/wiki/XDM
A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 138, 204109 (2013),
doi:10.1063/1.4705760
}
}
var space_group -type INTEGER {
default { 0 }
info {
The number of the space group of the crystal, as given
in the International Tables of Crystallography A (ITA).
This allows to give in input only the inequivalent atomic
positions. The positions of all the symmetry equivalent atoms
are calculated by the code. Used only when the atomic positions
are of type crystal_sg. See also @ref uniqueb,
@ref origin_choice, @ref rhombohedral
}
}
var uniqueb -type LOGICAL {
default { .FALSE. }
info {
Used only for monoclinic lattices. If .TRUE. the b
unique ibrav (-12 or -13) are used, and symmetry
equivalent positions are chosen assuming that the
two fold axis or the mirror normal is parallel to the
b axis. If .FALSE. it is parallel to the c axis.
}
}
var origin_choice -type INTEGER {
default { 1 }
info {
Used only for space groups that in the ITA allow
the use of two different origins. origin_choice=1,
means the first origin, while origin_choice=2 is the
second origin.
}
}
var rhombohedral -type LOGICAL {
default { .TRUE. }
info {
Used only for rhombohedral space groups.
When .TRUE. the coordinates of the inequivalent atoms are
given with respect to the rhombohedral axes, when .FALSE.
the coordinates of the inequivalent atoms are given with
respect to the hexagonal axes. They are converted internally
to the rhombohedral axes and @ref ibrav=5 is used in both cases.
}
}
group {
label { variables used only if @ref gate = .TRUE. }
var zgate -type REAL {
default { 0.5 }
info {
used only if @ref gate = .TRUE.
Specifies the position of the charged plate which represents
the counter charge in doped systems (@ref tot_charge .ne. 0).
In units of the unit cell length in @i z direction, @ref zgate in ]0,1[
Details of the gate potential can be found in
T. Brumme, M. Calandra, F. Mauri; PRB 89, 245406 (2014).
}
}
var relaxz -type LOGICAL {
default { .FALSE. }
info {
used only if @ref gate = .TRUE.
Allows the relaxation of the system towards the charged plate.
Use carefully and utilize either a layer of fixed atoms or a
potential barrier (@ref block=.TRUE.) to avoid the atoms moving to
the position of the plate or the dipole of the dipole
correction (@ref dipfield=.TRUE.).
}
}
var block -type LOGICAL {
default { .FALSE. }
info {
used only if @ref gate = .TRUE.
Adds a potential barrier to the total potential seen by the
electrons to mimic a dielectric in field effect configuration
and/or to avoid electrons spilling into the vacuum region for
electron doping. Potential barrier is from @ref block_1 to @ref block_2 and
has a height of block_height.
If @ref dipfield = .TRUE. then @ref eopreg is used for a smooth increase and
decrease of the potential barrier.
}
}
var block_1 -type REAL {
default { 0.45 }
info {
used only if @ref gate = .TRUE. and @ref block = .TRUE.
lower beginning of the potential barrier, in units of the
unit cell size along @i z, @ref block_1 in ]0,1[
}
}
var block_2 -type REAL {
default { 0.55 }
info {
used only if @ref gate = .TRUE. and @ref block = .TRUE.
upper beginning of the potential barrier, in units of the
unit cell size along @i z, @ref block_2 in ]0,1[
}
}
var block_height -type REAL {
default { 0.1 }
info {
used only if @ref gate = .TRUE. and @ref block = .TRUE.
Height of the potential barrier in Rydberg.
}
}
}
}
#
# namelist ELECTRONS
#
namelist ELECTRONS {
var electron_maxstep -type INTEGER {
default { 100 }
info {
maximum number of iterations in a scf step
}
}
var scf_must_converge -type LOGICAL {
default { .TRUE. }
info {
If .false. do not stop molecular dynamics or ionic relaxation
when electron_maxstep is reached. Use with care.
}
}
var conv_thr -type REAL {
default { 1.D-6 }
info {
Convergence threshold for selfconsistency:
estimated energy error < conv_thr
(note that conv_thr is extensive, like the total energy).
For non-self-consistent calculations, conv_thr is used
to set the default value of the threshold (ethr) for
iterative diagonalizazion: see @ref diago_thr_init
}
}
var adaptive_thr -type LOGICAL {
default { .FALSE }
info {
If .TRUE. this turns on the use of an adaptive @ref conv_thr for
the inner scf loops when using EXX.
}
}
var conv_thr_init -type REAL {
default { 1.D-3 }
info {
When @ref adaptive_thr = .TRUE. this is the convergence threshold
used for the first scf cycle.
}
}
var conv_thr_multi -type REAL {
default { 1.D-1 }
info {
When @ref adaptive_thr = .TRUE. the convergence threshold for
each scf cycle is given by:
max( @ref conv_thr, @ref conv_thr_multi * dexx )
}
}
var mixing_mode -type CHARACTER {
default { 'plain' }
options {
info { Available options are: }
opt -val 'plain' { charge density Broyden mixing }
opt -val 'TF' {
as above, with simple Thomas-Fermi screening
(for highly homogeneous systems)
}
opt -val 'local-TF' {
as above, with local-density-dependent TF screening
(for highly inhomogeneous systems)
}
}
}
var mixing_beta -type REAL {
default { 0.7D0 }
info {
mixing factor for self-consistency
}
}
var mixing_ndim -type INTEGER {
default { 8 }
info {
number of iterations used in mixing scheme.
If you are tight with memory, you may reduce it to 4 or so.
}
}
var mixing_fixed_ns -type INTEGER {
default { 0 }
info {
For DFT+U : number of iterations with fixed ns ( ns is the
atomic density appearing in the Hubbard term ).
}
}
var diagonalization -type CHARACTER {
default { 'david' }
options {
info { Available options are: }
opt -val 'david' {
Davidson iterative diagonalization with overlap matrix
(default). Fast, may in some rare cases fail.
}
opt -val 'cg' {
Conjugate-gradient-like band-by-band diagonalization.
Slower than 'david' but uses less memory and is
(a little bit) more robust.
}
opt -val {'ppcg'} {
PPCG iterative diagonalization
}
opt -val {'paro', 'ParO'} {
ParO iterative diagonalization
}
}
}
var diago_thr_init -type REAL {
info {
Convergence threshold (ethr) for iterative diagonalization
(the check is on eigenvalue convergence).
For scf calculations: default is 1.D-2 if starting from a
superposition of atomic orbitals; 1.D-5 if starting from a
charge density. During self consistency the threshold
is automatically reduced (but never below 1.D-13) when
approaching convergence.
For non-scf calculations: default is (@ref conv_thr/N elec)/10.
}
}
var diago_cg_maxiter -type INTEGER {
info {
For conjugate gradient diagonalization: max number of iterations
}
}
var diago_david_ndim -type INTEGER {
default { 4 }
info {
For Davidson diagonalization: dimension of workspace
(number of wavefunction packets, at least 2 needed).
A larger value may yield a smaller number of iterations in
the algorithm but uses more memory and more CPU time in
subspace diagonalization.
Try @ref diago_david_ndim=2 if you are tight on memory or if
the time spent in subspace diagonalization (cdiaghg/rdiaghg)
is significant compared to the time spent in h_psi
}
}
var diago_full_acc -type LOGICAL {
default { .FALSE. }
info {
If .TRUE. all the empty states are diagonalized at the same level
of accuracy of the occupied ones. Otherwise the empty states are
diagonalized using a larger threshold (this should not affect
total energy, forces, and other ground-state properties).
}
}
var efield -type REAL {
default { 0.D0 }
info {
Amplitude of the finite electric field (in Ry a.u.;
1 a.u. = 36.3609*10^10 V/m). Used only if @ref lelfield==.TRUE.
and if k-points (@ref K_POINTS card) are not automatic.
}
}
dimension efield_cart -start 1 -end 3 -type REAL {
default { (0.D0, 0.D0, 0.D0) }
info {
Finite electric field (in Ry a.u.=36.3609*10^10 V/m) in
cartesian axis. Used only if @ref lelfield==.TRUE. and if
k-points (@ref K_POINTS card) are automatic.
}
}
var efield_phase -type CHARACTER {
default { 'none' }
options {
info { Available options are: }
opt -val 'read' {
set the zero of the electronic polarization (with @ref lelfield==.true..)
to the result of a previous calculation
}
opt -val 'write' {
write on disk data on electronic polarization to be read in another
calculation
}
opt -val 'none' {
none of the above points
}
}
}
var startingpot -type CHARACTER {
options {
info { Available options are: }
opt -val 'atomic' {
starting potential from atomic charge superposition
(default for scf, *relax, *md)
}
opt -val 'file' {
start from existing "charge-density.xml" file in the
directory specified by variables @ref prefix and @ref outdir
For nscf and bands calculation this is the default
and the only sensible possibility.
}
}
}
var startingwfc -type CHARACTER {
default { 'atomic+random' }
options {
info { Available options are: }
opt -val 'atomic' {
Start from superposition of atomic orbitals.
If not enough atomic orbitals are available,
fill with random numbers the remaining wfcs
The scf typically starts better with this option,
but in some high-symmetry cases one can "loose"
valence states, ending up in the wrong ground state.
}
opt -val 'atomic+random' {
As above, plus a superimposed "randomization"
of atomic orbitals. Prevents the "loss" of states
mentioned above.
}
opt -val 'random' {
Start from random wfcs. Slower start of scf but safe.
It may also reduce memory usage in conjunction with
@ref diagonalization='cg'.
}
opt -val 'file' {
Start from an existing wavefunction file in the
directory specified by variables @ref prefix and @ref outdir.
}
}
}
var tqr -type LOGICAL {
default { .FALSE. }
info {
If .true., use a real-space algorithm for augmentation
charges of ultrasoft pseudopotentials and PAWsets.
Faster but numerically less accurate than the default
G-space algorithm. Use with care and after testing!
}
}
var real_space -type LOGICAL {
default { .FALSE. }
info {
If .true., exploit real-space localization to compute
matrix elements for nonlocal projectors. Faster and in
principle better scaling than the default G-space algorithm,
but numerically less accurate, may lead to some loss of
translational invariance. Use with care and after testing!
}
}
}
#
# NAMELIST IONS
#
namelist IONS {
label {
input this namelist only if @ref calculation == 'relax', 'md', 'vc-relax', or 'vc-md'
}
var ion_dynamics -type CHARACTER {
options {
info {
Specify the type of ionic dynamics.
For different type of calculation different possibilities are
allowed and different default values apply:
@b CASE ( @ref calculation == 'relax' )
}
opt -val 'bfgs' {
@b (default) use BFGS quasi-newton algorithm,
based on the trust radius procedure,
for structural relaxation
}
opt -val 'damp' {
use damped (quick-min Verlet)
dynamics for structural relaxation
Can be used for constrained
optimisation: see @ref CONSTRAINTS card
}
info {
@b CASE ( @ref calculation == 'md' )
}
opt -val 'verlet' {
@b (default) use Verlet algorithm to integrate
Newton's equation. For constrained
dynamics, see @ref CONSTRAINTS card
}
opt -val 'langevin' {
ion dynamics is over-damped Langevin
}
opt -val 'langevin-smc' {
over-damped Langevin with Smart Monte Carlo:
see R.J. Rossky, JCP, 69, 4628 (1978), doi:10.1063/1.436415
}
info {
@b CASE ( @ref calculation == 'vc-relax' )
}
opt -val 'bfgs' {
@b (default) use BFGS quasi-newton algorithm;
cell_dynamics must be 'bfgs' too
}
opt -val 'damp' {
use damped (Beeman) dynamics for
structural relaxation
}
info {
@b CASE ( @ref calculation == 'vc-md' )
}
opt -val 'beeman' {
@b (default) use Beeman algorithm to integrate
Newton's equation
}
}
}
var ion_positions -type CHARACTER {
default { 'default' }
options {
info { Available options are: }
opt -val 'default' {
if restarting, use atomic positions read from the
restart file; in all other cases, use atomic
positions from standard input.
}
opt -val 'from_input' {
restart the simulation with atomic positions read
from standard input, even if restarting.
}
}
}
var pot_extrapolation -type CHARACTER {
default { 'atomic' }
options {
info {
Used to extrapolate the potential from preceding ionic steps.
}
opt -val 'none' { no extrapolation }
opt -val 'atomic' {
extrapolate the potential as if it was a sum of
atomic-like orbitals
}
opt -val 'first_order' {
extrapolate the potential with first-order
formula
}
opt -val 'second_order' {
as above, with second order formula
}
info {
Note: 'first_order' and 'second-order' extrapolation make sense
only for molecular dynamics calculations
}
}
}
var wfc_extrapolation -type CHARACTER {
default { 'none' }
options {
info {
Used to extrapolate the wavefunctions from preceding ionic steps.
}
opt -val 'none' { no extrapolation }
opt -val 'first_order' {
extrapolate the wave-functions with first-order formula.
}
opt -val 'second_order' {
as above, with second order formula.
}
info {
Note: @b 'first_order' and @b 'second-order' extrapolation make sense
only for molecular dynamics calculations
}
}
}
var remove_rigid_rot -type LOGICAL {
default { .FALSE. }
info {
This keyword is useful when simulating the dynamics and/or the
thermodynamics of an isolated system. If set to true the total
torque of the internal forces is set to zero by adding new forces
that compensate the spurious interaction with the periodic
images. This allows for the use of smaller supercells.
BEWARE: since the potential energy is no longer consistent with
the forces (it still contains the spurious interaction with the
repeated images), the total energy is not conserved anymore.
However the dynamical and thermodynamical properties should be
in closer agreement with those of an isolated system.
Also the final energy of a structural relaxation will be higher,
but the relaxation itself should be faster.
}
}
group {
label {
variables used for molecular dynamics
}
var ion_temperature -type CHARACTER {
default { 'not_controlled' }
options {
info { Available options are: }
opt -val 'rescaling' {
control ionic temperature via velocity rescaling
(first method) see parameters @ref tempw, @ref tolp, and
@ref nraise (for VC-MD only). This rescaling method
is the only one currently implemented in VC-MD
}
opt -val 'rescale-v' {
control ionic temperature via velocity rescaling
(second method) see parameters @ref tempw and @ref nraise
}
opt -val 'rescale-T' {
scale temperature of the thermostat every @ref nraise steps
by @ref delta_t, starting from @ref tempw.
The temperature is controlled via velocitiy rescaling.
}
opt -val 'reduce-T' {
reduce temperature of the thermostat every @ref nraise steps
by the (negative) value @ref delta_t, starting from @ref tempw.
If @ref delta_t is positive, the target temperature is augmented.
The temperature is controlled via velocitiy rescaling.
}
opt -val 'berendsen' {
control ionic temperature using "soft" velocity
rescaling - see parameters @ref tempw and @ref nraise
}
opt -val 'andersen' {
control ionic temperature using Andersen thermostat
see parameters @ref tempw and @ref nraise
}
opt -val 'svr' {
control ionic temperature using stochastic-velocity rescaling
(Donadio, Bussi, Parrinello, J. Chem. Phys. 126, 014101, 2007),
with parameters @ref tempw and @ref nraise.
}
opt -val 'initial' {
initialize ion velocities to temperature @ref tempw
and leave uncontrolled further on
}
opt -val 'not_controlled' {
(default) ionic temperature is not controlled
}
}
}
var tempw -type REAL {
default { 300.D0 }
info {
Starting temperature (Kelvin) in MD runs
target temperature for most thermostats.
}
}
var tolp -type REAL {
default { 100.D0 }
info {
Tolerance for velocity rescaling. Velocities are rescaled if
the run-averaged and target temperature differ more than tolp.
}
}
var delta_t -type REAL {
default { 1.D0 }
info {
if @ref ion_temperature == 'rescale-T' :
at each step the instantaneous temperature is multiplied
by delta_t; this is done rescaling all the velocities.
if @ref ion_temperature == 'reduce-T' :
every 'nraise' steps the instantaneous temperature is
reduced by -@ref delta_t (i.e. @ref delta_t < 0 is added to T)
The instantaneous temperature is calculated at the end of
every ionic move and BEFORE rescaling. This is the temperature
reported in the main output.
For @ref delta_t < 0, the actual average rate of heating or cooling
should be roughly C*delta_t/(nraise*dt) (C=1 for an
ideal gas, C=0.5 for a harmonic solid, theorem of energy
equipartition between all quadratic degrees of freedom).
}
}
var nraise -type INTEGER {
default { 1 }
info {
if @ref ion_temperature == 'reduce-T' :
every @ref nraise steps the instantaneous temperature is
reduced by -@ref delta_t (i.e. @ref delta_t is added to the temperature)
if @ref ion_temperature == 'rescale-v' :
every @ref nraise steps the average temperature, computed from
the last @ref nraise steps, is rescaled to @ref tempw
if @ref ion_temperature == 'rescaling' and @ref calculation == 'vc-md' :
every @ref nraise steps the instantaneous temperature
is rescaled to @ref tempw
if @ref ion_temperature == 'berendsen' :
the "rise time" parameter is given in units of the time step:
tau = nraise*dt, so dt/tau = 1/nraise
if @ref ion_temperature == 'andersen' :
the "collision frequency" parameter is given as nu=1/tau
defined above, so nu*dt = 1/nraise
if @ref ion_temperature == 'svr' :
the "characteristic time" of the thermostat is set to
tau = nraise*dt
}
}
var refold_pos -type LOGICAL {
default { .FALSE. }
info {
This keyword applies only in the case of molecular dynamics or
damped dynamics. If true the ions are refolded at each step into
the supercell.
}
}
}
group {
label {
keywords used only in BFGS calculations
}
var upscale -type REAL {
default { 100.D0 }
info {
Max reduction factor for @ref conv_thr during structural optimization
@ref conv_thr is automatically reduced when the relaxation
approaches convergence so that forces are still accurate,
but @ref conv_thr will not be reduced to less that @ref conv_thr / @ref upscale.
}
}
var bfgs_ndim -type INTEGER {
default { 1 }
info {
Number of old forces and displacements vectors used in the
PULAY mixing of the residual vectors obtained on the basis
of the inverse hessian matrix given by the BFGS algorithm.
When @ref bfgs_ndim = 1, the standard quasi-Newton BFGS method is
used.
(bfgs only)
}
}
var trust_radius_max -type REAL {
default { 0.8D0 }
info {
Maximum ionic displacement in the structural relaxation.
(bfgs only)
}
}
var trust_radius_min -type REAL {
default { 1.D-3 }
info {
Minimum ionic displacement in the structural relaxation
BFGS is reset when @ref trust_radius < @ref trust_radius_min.
(bfgs only)
}
}
var trust_radius_ini -type REAL {
default { 0.5D0 }
info {
Initial ionic displacement in the structural relaxation.
(bfgs only)
}
}
var w_1 -type REAL { default { 0.01D0 }; see { w_2 } }
var w_2 -type REAL {
default { 0.5D0 }
info {
Parameters used in line search based on the Wolfe conditions.
(bfgs only)
}
}
}
}
#
# namelist CELL
#
namelist CELL {
label {
input this namelist only if @ref calculation == 'vc-relax' or 'vc-md'
}
var cell_dynamics -type CHARACTER {
options {
info {
Specify the type of dynamics for the cell.
For different type of calculation different possibilities
are allowed and different default values apply:
@b CASE ( @ref calculation == 'vc-relax' )
}
opt -val 'none' { no dynamics }
opt -val 'sd' { steepest descent ( not implemented ) }
opt -val 'damp-pr' {
damped (Beeman) dynamics of the Parrinello-Rahman extended lagrangian
}
opt -val 'damp-w' {
damped (Beeman) dynamics of the new Wentzcovitch extended lagrangian
}
opt -val 'bfgs' {
BFGS quasi-newton algorithm @b (default)
@ref ion_dynamics must be @b 'bfgs' too
}
info {
@b CASE ( @ref calculation == 'vc-md' )
}
opt -val 'none' { no dynamics }
opt -val 'pr' {
(Beeman) molecular dynamics of the Parrinello-Rahman extended lagrangian
}
opt -val 'w' {
(Beeman) molecular dynamics of the new Wentzcovitch extended lagrangian
}
}
}
var press -type REAL {
default { 0.D0 }
info {
Target pressure [KBar] in a variable-cell md or relaxation run.
}
}
var wmass -type REAL {
default {
0.75*Tot_Mass/pi**2 for Parrinello-Rahman MD;
0.75*Tot_Mass/pi**2/Omega**(2/3) for Wentzcovitch MD
}
info {
Fictitious cell mass [amu] for variable-cell simulations
(both 'vc-md' and 'vc-relax')
}
}
var cell_factor -type REAL {
default { 2.0 for variable-cell calculations, 1.0 otherwise }
info {
Used in the construction of the pseudopotential tables.
It should exceed the maximum linear contraction of the
cell during a simulation.
}
}
var press_conv_thr -type REAL {
default { 0.5D0 Kbar }
info {
Convergence threshold on the pressure for variable cell
relaxation ('vc-relax' : note that the other convergence
thresholds for ionic relaxation apply as well).
}
}
var cell_dofree -type CHARACTER {
default { 'all' }
options {
info {
Select which of the cell parameters should be moved:
}
opt -val 'all' { all axis and angles are moved }
opt -val 'ibrav' { all axis and angles are moved, but the lattice remains consistent with the initial ibrav choice }
opt -val 'x' { only the x component of axis 1 (v1_x) is moved }
opt -val 'y' { only the y component of axis 2 (v2_y) is moved }
opt -val 'z' { only the z component of axis 3 (v3_z) is moved }
opt -val 'xy' { only v1_x and v2_y are moved }
opt -val 'xz' { only v1_x and v3_z are moved }
opt -val 'yz' { only v2_y and v3_z are moved }
opt -val 'xyz' { only v1_x, v2_y, v3_z are moved }
opt -val 'shape' { all axis and angles, keeping the volume fixed }
opt -val 'volume' { the volume changes, keeping all angles fixed (i.e. only celldm(1) changes) }
opt -val '2Dxy' { only x and y components are allowed to change }
opt -val '2Dshape' { as above, keeping the area in xy plane fixed }
opt -val 'epitaxial_ab' {fix axis 1 and 2 while allowing axis 3 to move }
opt -val 'epitaxial_ac' {fix axis 1 and 3 while allowing axis 2 to move }
opt -val 'epitaxial_bc' {fix axis 2 and 3 while allowing axis 1 to move }
info {
BEWARE: if axis are not orthogonal, some of these options do not
work (symmetry is broken). If you are not happy with them,
edit subroutine init_dofree in file Modules/cell_base.f90
}
}
}
}
#
# card ATOMIC_SPECIES
#
card ATOMIC_SPECIES {
syntax {
table atomic_species {
rows -start 1 -end ntyp {
col X -type CHARACTER {
info {
label of the atom. Acceptable syntax:
chemical symbol X (1 or 2 characters, case-insensitive)
or chemical symbol plus a number or a letter, as in
"Xn" (e.g. Fe1) or "X_*" or "X-*" (e.g. C1, C_h;
max total length cannot exceed 3 characters)
}
}
col Mass_X -type REAL {
info {
mass of the atomic species [amu: mass of C = 12]
Used only when performing Molecular Dynamics run
or structural optimization runs using Damped MD.
Not actually used in all other cases (but stored
in data files, so phonon calculations will use
these values unless other values are provided)
}
}
col PseudoPot_X -type CHARACTER {
info {
File containing PP for this species.
The pseudopotential file is assumed to be in the new UPF format.
If it doesn't work, the pseudopotential format is determined by
the file name:
*.vdb or *.van Vanderbilt US pseudopotential code
*.RRKJ3 Andrea Dal Corso's code (old format)
none of the above old PWscf norm-conserving format
}
}
}
}
}
}
#
# card ATOMIC_POSITIONS
#
card ATOMIC_POSITIONS {
flag atompos_unit -use optional {
enum { alat | bohr | angstrom | crystal | crystal_sg }
default { (DEPRECATED) alat }
options {
info {
Units for ATOMIC_POSITIONS:
}
opt -val alat {
atomic positions are in cartesian coordinates, in
units of the lattice parameter (either celldm(1)
or A). If no option is specified, 'alat' is assumed;
not specifying units is DEPRECATED and will no
longer be allowed in the future
}
opt -val bohr {
atomic positions are in cartesian coordinate,
in atomic units (i.e. Bohr radii)
}
opt -val angstrom {
atomic positions are in cartesian coordinates, in Angstrom
}
opt -val crystal {
atomic positions are in crystal coordinates, i.e.
in relative coordinates of the primitive lattice
vectors as defined either in card @ref CELL_PARAMETERS
or via the ibrav + celldm / a,b,c... variables
}
opt -val crystal_sg {
atomic positions are in crystal coordinates, i.e.
in relative coordinates of the primitive lattice.
This option differs from the previous one because
in this case only the symmetry inequivalent atoms
are given. The variable @ref space_group must indicate
the space group number used to find the symmetry
equivalent atoms. The other variables that control
this option are uniqueb, origin_choice, and
rhombohedral.
}
}
}
choose {
when -test "calculation == 'bands' OR calculation == 'nscf'" {
message {
Specified atomic positions will be IGNORED and those from the
previous scf calculation will be used instead !!!
}
}
otherwise {
syntax {
table atomic_coordinates {
rows -start 1 -end nat {
col X -type CHARACTER {
info { label of the atom as specified in @ref ATOMIC_SPECIES }
}
colgroup -type REAL {
info {
atomic positions
NOTE: each atomic coordinate can also be specified as a simple algebraic expression.
To be interpreted correctly expression must NOT contain any blank
space and must NOT start with a "+" sign. The available expressions are:
+ (plus), - (minus), / (division), * (multiplication), ^ (power)
All numerical constants included are considered as double-precision numbers;
i.e. 1/2 is 0.5, not zero. Other functions, such as sin, sqrt or exp are
not available, although sqrt can be replaced with ^(1/2).
Example:
C 1/3 1/2*3^(-1/2) 0
is equivalent to
C 0.333333 0.288675 0.000000
Please note that this feature is NOT supported by XCrysDen (which will
display a wrong structure, or nothing at all).
When atomic positions are of type crystal_sg coordinates can be given
in the following four forms (Wyckoff positions):
C 1a
C 8g x
C 24m x y
C 48n x y z
The first form must be used when the Wyckoff letter determines uniquely
all three coordinates, forms 2,3,4 when the Wyckoff letter and 1,2,3
coordinates respectively are needed.
The forms:
C 8g x x x
C 24m x x y
are not allowed, but
C x x x
C x x y
C x y z
are correct.
}
col x
col y
col z
}
optional {
colgroup -type INTEGER {
info {
component i of the force for this atom is multiplied by if_pos(i),
which must be either 0 or 1. Used to keep selected atoms and/or
selected components fixed in MD dynamics or
structural optimization run.
With crystal_sg atomic coordinates the constraints are copied in all equivalent
atoms.
}
default { 1 }
col if_pos(1)
col if_pos(2)
col if_pos(3)
}
}
}
}
}
}
}
}
#
# K_POINTS
#
card K_POINTS {
flag kpoint_type -use optional {
enum { tpiba | automatic | crystal | gamma | tpiba_b | crystal_b | tpiba_c | crystal_c }
default { tbipa }
options {
info {
K_POINTS options are:
}
opt -val tpiba {
read k-points in cartesian coordinates,
in units of 2 pi/a (default)
}
opt -val automatic {
automatically generated uniform grid of k-points, i.e,
generates ( nk1, nk2, nk3 ) grid with ( sk1, sk2, sk3 ) offset.
nk1, nk2, nk3 as in Monkhorst-Pack grids
k1, k2, k3 must be 0 ( no offset ) or 1 ( grid displaced
by half a grid step in the corresponding direction )
BEWARE: only grids having the full symmetry of the crystal
work with tetrahedra. Some grids with offset may not work.
}
opt -val crystal {
read k-points in crystal coordinates, i.e. in relative
coordinates of the reciprocal lattice vectors
}
opt -val gamma {
use k = 0 (no need to list k-point specifications after card)
In this case wavefunctions can be chosen as real,
and specialized subroutines optimized for calculations
at the gamma point are used (memory and cpu requirements
are reduced by approximately one half).
}
opt -val tpiba_b {
Used for band-structure plots.
See Doc/brillouin_zones.pdf for usage of BZ labels;
otherwise, k-points are in units of 2 pi/a.
nks points specify nks-1 lines in reciprocal space.
Every couple of points identifies the initial and
final point of a line. pw.x generates N intermediate
points of the line where N is the weight of the first point.
}
opt -val crystal_b {
As tpiba_b, but k-points are in crystal coordinates.
See Doc/brillouin_zones.pdf for usage of BZ labels.
}
opt -val tpiba_c {
Used for band-structure contour plots.
k-points are in units of 2 @i pi/a. nks must be 3.
3 k-points k_0, k_1, and k_2 specify a rectangle
in reciprocal space of vertices k_0, k_1, k_2,
k_1 + k_2 - k_0: k_0 + \alpha (k_1-k_0)+
\beta (k_2-k_0) with 0 <\alpha,\beta < 1.
The code produces a uniform mesh n1 x n2
k points in this rectangle. n1 and n2 are
the weights of k_1 and k_2. The weight of k_0
is not used.
}
opt -val crystal_c {
As tpiba_c, but k-points are in crystal coordinates.
}
}
}
choose {
when -test "tpiba OR crystal OR tpiba_b OR crystal_b OR tpiba_c OR crystal_c" {
syntax -flag {tpiba | crystal | tpiba_b | crystal_b | tpiba_c | crystal_c } {
line {
var nks -type INTEGER {
info {Number of supplied special k-points.}
}
}
table kpoints {
rows -start 1 -end nks {
colgroup -type REAL {
col xk_x
col xk_y
col xk_z
col wk
info {
Special k-points (xk_x/y/z) in the irreducible Brillouin Zone
(IBZ) of the lattice (with all symmetries) and weights (wk)
See the literature for lists of special points and
the corresponding weights.
If the symmetry is lower than the full symmetry
of the lattice, additional points with appropriate
weights are generated. Notice that such procedure
assumes that ONLY k-points in the IBZ are provided in input
In a non-scf calculation, weights do not affect the results.
If you just need eigenvalues and eigenvectors (for instance,
for a band-structure plot), weights can be set to any value
(for instance all equal to 1).
}
}
}
}
}
}
elsewhen -test "automatic" {
syntax -flag {automatic} {
line {
vargroup -type INTEGER {
var nk1
var nk2
var nk3
info {
These parameters specify the k-point grid
(nk1 x nk2 x nk3) as in Monkhorst-Pack grids.
}
}
vargroup -type INTEGER {
var sk1
var sk2
var sk3
info {
The grid offsets; sk1, sk2, sk3 must be
0 ( no offset ) or 1 ( grid displaced by
half a grid step in the corresponding direction ).
}
}
}
}
}
elsewhen -test "gamma" {
syntax -flag {gamma} {}
}
}
}
#
# CELL_PARAMETERS
#
card CELL_PARAMETERS {
flag lattice_type -use optional {
enum { alat | bohr | angstrom }
info {
Unit for lattice vectors; options are:
@b 'bohr' / @b 'angstrom':
lattice vectors in bohr-radii / angstrom.
In this case the lattice parameter alat = sqrt(v1*v1).
@b 'alat' / nothing specified:
lattice vectors in units of the lattice parameter (either
@ref celldm(1) or @ref A). Not specifying units is DEPRECATED
and will not be allowed in the future.
If neither unit nor lattice parameter are specified,
'bohr' is assumed - DEPRECATED, will no longer be allowed
}
}
label {
Optional card, needed only if @ref ibrav == 0 is specified, ignored otherwise !
}
syntax {
table lattice {
cols -start 1 -end 3 {
rowgroup -type REAL {
info {
Crystal lattice vectors (in cartesian axis):
v1(1) v1(2) v1(3) ... 1st lattice vector
v2(1) v2(2) v2(3) ... 2nd lattice vector
v3(1) v3(2) v3(3) ... 3rd lattice vector
}
row v1
row v2
row v3
}
}
}
}
}
#
# CONSTRAINTS
#
card CONSTRAINTS {
label {
Optional card, used for constrained dynamics or constrained optimisations
(only if @ref ion_dynamics=='damp' or 'verlet', variable-cell excepted)
}
message {
When this card is present the SHAKE algorithm is automatically used.
}
syntax {
line {
var nconstr -type INTEGER {
info { Number of constraints. }
}
optional {
var constr_tol -type REAL {
info { Tolerance for keeping the constraints satisfied. }
}
}
}
table constraints_table {
rows -start 1 -end nconstr {
col constr_type -type CHARACTER {
options {
info {
Type of constraint :
}
opt -val 'type_coord' {
constraint on global coordination-number, i.e. the
average number of atoms of type B surrounding the
atoms of type A. The coordination is defined by
using a Fermi-Dirac.
(four indexes must be specified).
}
opt -val 'atom_coord' {
constraint on local coordination-number, i.e. the
average number of atoms of type A surrounding a
specific atom. The coordination is defined by
using a Fermi-Dirac.
(four indexes must be specified).
}
opt -val 'distance' {
constraint on interatomic distance
(two atom indexes must be specified).
}
opt -val 'planar_angle' {
constraint on planar angle
(three atom indexes must be specified).
}
opt -val 'torsional_angle' {
constraint on torsional angle
(four atom indexes must be specified).
}
opt -val 'bennett_proj' {
constraint on the projection onto a given direction
of the vector defined by the position of one atom
minus the center of mass of the others.
G. Roma, J.P. Crocombette: J. Nucl. Mater. 403, 32 (2010),
doi:10.1016/j.jnucmat.2010.06.001
}
}
}
colgroup {
col constr(1)
col constr(2)
conditional {
col constr(3)
col constr(4)
}
info {
These variables have different meanings for different constraint types:
@b 'type_coord' :
@i constr(1) is the first index of the atomic type involved
@i constr(2) is the second index of the atomic type involved
@i constr(3) is the cut-off radius for estimating the coordination
@i constr(4) is a smoothing parameter
@b 'atom_coord' :
@i constr(1) is the atom index of the atom with constrained coordination
@i constr(2) is the index of the atomic type involved in the coordination
@i constr(3) is the cut-off radius for estimating the coordination
@i constr(4) is a smoothing parameter
@b 'distance' :
atoms indices object of the constraint, as they appear in
the @ref ATOMIC_POSITIONS card
@b 'planar_angle', @b 'torsional_angle' :
atoms indices object of the constraint, as they appear in the
@ref ATOMIC_POSITIONS card (beware the order)
@b 'bennett_proj' :
@i constr(1) is the index of the atom whose position is constrained.
@i constr(2:4) are the three coordinates of the vector that specifies
the constraint direction.
}
}
optional {
col constr_target -type REAL {
info {
Target for the constrain ( angles are specified in degrees ).
This variable is optional.
}
}
}
}
}
}
}
#
# card OCCUPATIONS
#
card OCCUPATIONS {
label { Optional card, used only if @ref occupations == 'from_input', ignored otherwise ! }
syntax {
table occupations_table {
cols -start 1 -end nbnd {
row f_inp1 -type REAL {
info {
Occupations of individual states (MAX 10 PER ROW).
For spin-polarized calculations, these are majority spin states.
}
}
conditional {
row f_inp2 -type REAL {
info {
Occupations of minority spin states (MAX 10 PER ROW)
To be specified only for spin-polarized calculations.
}
}
}
}
}
}
}
#
# card ATOMIC_FORCES
#
card ATOMIC_FORCES {
label { Optional card used to specify external forces acting on atoms. }
message {
BEWARE: if the sum of external forces is not zero, the center of mass of
the system will move
}
syntax {
table atomic_forces {
rows -start 1 -end nat {
col X -type CHARACTER {
info { label of the atom as specified in @ref ATOMIC_SPECIES }
}
colgroup -type REAL {
info { external force on atom X (cartesian components, Ry/a.u. units)
}
col fx
col fy
col fz
}
}
}
}
}
}
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