mirror of https://gitlab.com/QEF/q-e.git
100 lines
4.1 KiB
Plaintext
100 lines
4.1 KiB
Plaintext
|
|
This example shows how to use pw2wannier90.x in conjunction with
|
|
Wannier90 (http://www.wannier.org) to obtain maximally-localised
|
|
Wannier functions (MLWFs) for the valence bands of diamond.
|
|
Wannier90 may be run in two modes, 'library' and 'standalone',
|
|
and both of these are demonstrated.
|
|
|
|
The Wannier90 code and library (available for download from
|
|
http://www.wannier.org under the GNU General Public License) are required.
|
|
For operation in library mode, the pw2wannier90 post-processing code must
|
|
be linked at compile time to the Wannier90 library. Instructions for
|
|
compilation of Wannier90 can be found in the documentation that comes with
|
|
the distribution.
|
|
|
|
The calculation proceeds as follows (for the meaning of the cited input
|
|
variables see the bottom of this file)
|
|
|
|
1) make a self-consistent calculation for diamond (input=diamond.scf.in,
|
|
output=diamond.scf.out). The number of computed bands is internally
|
|
computed as half the number of electrons in the unit cell
|
|
(4 in this case).
|
|
|
|
2) make a non-self-consistent calculation for diamond
|
|
(input=diamond.nscf.in, output=diamond.nscf.out).
|
|
The variable nbnd is explicitly set to 4 so that just the 4 valence
|
|
bands are calculated. The list of k-points given in input is the
|
|
list of points where the bands are computed. The k-points must form
|
|
a uniform Monkhorst-Pack mesh.
|
|
|
|
3) STAND-ALONE MODE
|
|
|
|
(3a) run Wannier90 (input=wannier.sa.win, output=wannier.sa.wout) to
|
|
generate a list of the required overlap elements between states at
|
|
different k-points. This information is written to a file called
|
|
diamond.sa.nnkp
|
|
|
|
(3b) run pw2wannier90 (input=diamond.pw2wan.sa.in,
|
|
output=diamond.pw2wan.sa.out) to compute the overlap between Bloch
|
|
states, the projections for the starting guess and the eigenvalue
|
|
of each Bloch eigenstate (written to the diamond.sa.mmn,
|
|
diamond.sa.amn and diamond.sa.eig files, respectively).
|
|
|
|
(3c) run Wannier90 (input=wannier.sa.win, output=wannier.sa.wout) to
|
|
obtain the MLWF centres and spreads.
|
|
|
|
4) LIBRARY MODE
|
|
|
|
!! pw2wannier90.x has to be compiled with the -D__WANLIB and
|
|
!! libwannier.a has to be linked
|
|
|
|
(4a) run pw2wannier90 in library mode to obtain the MLWF centres
|
|
and spreads (input=diamond.lib.win, diamond.pw2wan.lib.in,
|
|
output=diamond.lib.wout, diamond.pw2wan.lib.out).
|
|
|
|
N.B.
|
|
|
|
(i) The WAN_DIR variable in the run_example script must be set to the
|
|
directory of the wannier90 executable.
|
|
|
|
(ii) Multiple CPUs: distribution of k-points (the -npool command line option)
|
|
is not yet supported, only G-vectors.
|
|
|
|
(iii) To run in library mode, pw2wannier90 must be linked to the wannier
|
|
library. To do so, compile the Wannier90 library, libwannier.a,
|
|
following the instructions in the Wannier90 documentation (for the
|
|
impatient, type 'make lib' in the Wannier90 root directory). Then make
|
|
the following changes to the espresso make.sys file, and recompile
|
|
pw2wannier90:
|
|
|
|
+ Add -D__WANLIB to the DFLAGS variable
|
|
DFLAGS = -D__WANLIB ...
|
|
|
|
+ Add a new variable WANLIB to specify location of Wannier library
|
|
WANLIB = -L/path/of/wannier/library -lwannier
|
|
|
|
+ Add $(WANLIB) to the LIBS variable
|
|
LIBS = $(WANLIB) $(LAPACK_LIBS) $(BLAS_LIBS) ...
|
|
|
|
Input variables for pw2wannier90:
|
|
|
|
outdir : location of temporary output files
|
|
prefix : pwscf filename prefix
|
|
seedname : wannier90 input/output filename prefix
|
|
wan_mode : 'standalone' or 'library' [1]
|
|
write_mmn : (logical) compute M_mn matrix [1]
|
|
write_amn : (logical) compute A_mn matrix [1]
|
|
write_unk : (logical) write wavefunctions to file [1]
|
|
wvfn_formatted : (logical) formatted or unformatted output for wavefunctions
|
|
reduce_unk : (logical) output wavefunctions on a coarse grid to save memory
|
|
spin_component : 'none', 'up' or 'down'
|
|
|
|
|
|
Please report problems and suggestions to Stefano de Gironcoli
|
|
(degironc@sissa.it), Arash Mostofi (mostofi@mit.edu) and
|
|
Jonathan Yates (jry20@cam.ac.uk).
|
|
|
|
|
|
[1] For more details see Wannier90 documentation at http://www.wannier.org
|
|
|