mirror of https://github.com/abinit/abinit.git
110 lines
4.0 KiB
Plaintext
110 lines
4.0 KiB
Plaintext
# Finite difference calculation of the clamped-ion
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# piezoelectric constants of AlP
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#
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# The calculation proceeds by computing the change in cell
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# polarization by a Berrys phase formula, due to changes
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# in the strain of the unit cell. "Clamped-ion" refers to the
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# fact that the ions move with the strains but are not
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# allowed to relax to their new equilibrium positions
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# Berry phase calculation of the polarization
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# berryopt -1 triggers the implementation of M. Viethen
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berryopt -1
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# three cell geometries will be computed
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ndtset 3
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#Definition of the unit cell
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acell 3*7.2728565836E+00
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# rprim = strain tensor x rprim0, where
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# rprim0 is the unstrained rprim
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# strain: e4 = 0.00
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rprim1
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0.0000000000E+00 7.0710678119E-01 7.0710678119E-01
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7.0710678119E-01 0.0000000000E+00 7.0710678119E-01
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7.0710678119E-01 7.0710678119E-01 0.0000000000E+00
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#strain: e4 = 0.01
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rprim2
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0.0000000000E+00 7.1064231509E-01 7.1064231509E-01
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7.0710678119E-01 3.535533906E-03 7.0710678119E-01
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7.0710678119E-01 7.0710678119E-01 3.535533906E-03
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# strain: e4 = -0.01
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rprim3
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0.0000000000E+00 7.0357124728E-01 7.0357124728E-01
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7.0710678119E-01 -3.535533906E-03 7.0710678119E-01
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7.0710678119E-01 7.0710678119E-01 -3.535533906E-03
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tolsym 1.0e-8 # Since we make rather small lattice vector changes, with the default value of tolsym
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# ABINIT will recognize that we are close to a more symmetric
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# configuration, and will resymmetrize the primitive vectors, something we want to avoid ...
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#Definition of the atom types and pseudopotentials
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ntypat 2 # two types of atoms
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znucl 15 13 # the atom types are Phosphorous and Aluminum
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# the following norm-conserving pseudopotentials are stored in the abinit distribution, but are freely
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# available through www.pseudo-dojo.org
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# this set uses the Perdew-Wang parameterization of LDA for the xc model
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pp_dirpath "$ABI_PSPDIR"
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pseudos "Psdj_nc_sr_04_pw_std_psp8/P.psp8, Psdj_nc_sr_04_pw_std_psp8/Al.psp8"
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#Definition of the atoms
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natom 2 # two atoms in the cell
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typat 1 2 # type 1 is Phosphorous, type 2 is Aluminum (order defined by znucl above and pseudos list)
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nband 4 # nband is restricted here to the number of filled bands only, no empty bands. The theory of
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# the Berrys phase polarization formula assumes filled bands only. Our pseudopotential choice
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# includes 5 valence electrons on P, 3 on Al, for 8 total in the primitive unit cell, hence
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# 4 filled bands.
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#atomic positions, given in units of the cell vectors. Thus as the cell vectors
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#change due to strain the atoms will move as well.
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xred
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1/4 1/4 1/4
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0 0 0
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#Numerical parameters of the calculation : planewave basis set and k point grid
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ecut 5 # this value is very low but is used here to achieve very low calculation times.
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# in a production environment this should be checked carefully for convergence and
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# a more reasonable value is probably around 20
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ecutsm 0.5
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dilatmx 1.05
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ngkpt 6 6 6
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nshiftk 4 # this Monkhorst-Pack shift pattern is used so that the symmetry of the shifted grid
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# is correct. A gamma-centered grid would also have the correct symmetry but would be
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# less efficient.
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shiftk 0.5 0.5 0.5
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0.5 0.0 0.0
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0.0 0.5 0.0
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0.0 0.0 0.5
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#Parameters for the SCF procedure
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toldfe 1.0d-15
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nstep 8
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# suppress printing of density, wavefunctions, etc for this tutorial
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prtwf 0
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prtden 0
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prteig 0
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##############################################################
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# This section is used only for regression testing of ABINIT #
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##############################################################
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#%%<BEGIN TEST_INFO>
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#%% [setup]
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#%% executable = abinit
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#%% [files]
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#%% files_to_test =
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#%% tpolarization_4.abo, tolnlines= 10, tolabs= 9.999e-9, tolrel= 1.224e-04
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#%% [paral_info]
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#%% max_nprocs = 2
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#%% [extra_info]
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#%% authors = J. Zwanziger, M. Veithen
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#%% keywords = NC, DFPT
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#%% description =
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#%% Finite difference calculation of the clamped-ion
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#%% piezoelectric constants of AlP
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#%%<END TEST_INFO>
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