Hi there,
I am trying to perform a berry phase calculation with a homogeneous
electric field (lelfield=.true.) however I receive the "wrong k-strings?" in
c_phase error while running in parallel with OpenMPI on 4 processors:
>From the documentation, if K_POINTS is automatic, then field strength should
>be specified in cartesian coordinates (efield_cart(i)) and 'efield' is not
>used, however reading the berry phase documentation says that the direction of
>the efield is taken along gdir when a homogeneous electric field is applied.
Must I still specify efield_cart values when gdir is specified (it would seem
so)? The code doesn't complain until after bandstructure computation. I have
tried efield calculation with the following specification (see below for input
file used):
efield_cart(1) = 0.0001,
efield_cart(2) = 0,
efield_cart(3) = 0,
which results in the electric field existing in two directions in crystal
reference system, but the error is the same whether I do or do not include
these fields and leave efield=0.0001
My process is as follows:
- scf calculation of trigonal alpha-Al2O3 cell (input crystal is correct)
- band structure calculation
- Berry phase calculation *without* electric field (this works and output is
correct) with input:
&CONTROL
title = 'alpha-Alumina' ,
calculation = 'nscf' ,
outdir = '${PWD}' ,
pseudo_dir = '${PWD}/pseudo/' ,
verbosity = 'high' ,
prefix = 'run_${RUN_NUMBER}',
lberry = .true.,
gdir = 1,
nppstr = 10,
lelfield = .false.,
nberrycyc = 1
/
&SYSTEM
ibrav = 5,
A = 5.136,
cosAB = 0.56956647115,
nat = 10,
ntyp = 2,
occupations = 'fixed',
ecutwfc = 50,
ecutrho = 350,
nbnd = 48
/
&ELECTRONS
conv_thr = 1d-8,
diagonalization = 'cg',
mixing_beta = 0.7,
electron_maxstep = 200,
efield = 0,
efield_phase = 'write'
/
ATOMIC_SPECIES
O 15.99900 O.pbe-van_ak.UPF
Al 26.98200 Al.pbe-n-van.UPF
ATOMIC_POSITIONS crystal
O 0.556000000 0.944000000 0.250000000
O 0.444000000 0.056000000 0.750000000
O 0.250000000 0.556000000 0.944000000
O 0.750000000 0.444000000 0.056000000
O 0.944000000 0.250000000 0.556000000
O 0.056000000 0.750000000 0.444000000
Al 0.352000000 0.352000000 0.352000000
Al 0.648000000 0.648000000 0.648000000
Al 0.148000000 0.148000000 0.148000000
Al 0.852000000 0.852000000 0.852000000
K_POINTS automatic
10 4 4 0 0 0
- Then Berry phase calculation *with* electric field:
&CONTROL
title = 'alpha-Alumina' ,
calculation = 'nscf' ,
outdir = '${PWD}' ,
pseudo_dir = '${PWD}/pseudo/' ,
verbosity = 'high' ,
prefix = 'run_${RUN_NUMBER}',
lberry = .true.,
gdir = 1,
nppstr = 10,
lelfield = .true.,
nberrycyc = 1
/
&SYSTEM
ibrav = 5,
A = 5.136,
cosAB = 0.56956647115,
nat = 10,
ntyp = 2,
occupations = 'fixed',
ecutwfc = 50,
ecutrho = 350,
nbnd = 48,
nosym = .false.
/
&ELECTRONS
conv_thr = 1d-8,
diagonalization = 'cg',
mixing_beta = 0.7,
electron_maxstep = 200,
efield = 0.0001,
efield_phase = 'read'
/
ATOMIC_SPECIES
O 15.99900 O.pbe-van_ak.UPF
Al 26.98200 Al.pbe-n-van.UPF
ATOMIC_POSITIONS crystal
O 0.556000000 0.944000000 0.250000000
O 0.444000000 0.056000000 0.750000000
O 0.250000000 0.556000000 0.944000000
O 0.750000000 0.444000000 0.056000000
O 0.944000000 0.250000000 0.556000000
O 0.056000000 0.750000000 0.444000000
Al 0.352000000 0.352000000 0.352000000
Al 0.648000000 0.648000000 0.648000000
Al 0.148000000 0.148000000 0.148000000
Al 0.852000000 0.852000000 0.852000000
K_POINTS automatic
10 4 4 0 0 0
My last thought is that when the electric field is specified in cartesian
coordinates as above, the fact that the field in the crystal reference system
is along two directions causes the problem, I have struggled to get the field
to exist along one direction in the crystal reference system (does anyone know
a reference I could use to do this properly?). Maybe the sensible thing to do
is not use automatic K_POINTS?
Kindest regards,
Louis
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