[Pw_forum] LO -TO Splitting
Shyam
slgphy at rediffmail.com
Mon Nov 10 17:10:24 CET 2008
Hello all,I am trying to get the LO-TO splitting in GaAs. But I am
a bit confused about the pseudo potential to be used. I have done
calculations using both the ultrasoft pseudopotential (USPP) and
the normconserving (NCPP). Both of these are giving me almost similar
electronic DOS whereas phonon DOS differ in two cases. The phonon DOS which I have got using USPP is matching with
the reported one and that I have got using NCPP is not matching. The input files used in two cases are as follows,***********************************************************************USPP***********************************************************************
cat > gaas.scf.in << EOF
&control
calculation='scf'
restart_mode='from_scratch',
tstress = .true.
tprnfor = .true.
prefix='gaas',
pseudo_dir = '$PSEUDO_DIR/',
outdir='$TMP_DIR/'
/
&system
ibrav= 2, celldm(1) =10.68, nat= 2, ntyp= 2,
ecutwfc =18.0, ecutrho =1700,
/
&electrons
conv_thr = 1.0d-8
mixing_beta = 0.7
/
ATOMIC_SPECIES
Ga 69.72 Ga.pbe-nsp-van.UPF
As 74.92 As.pbe-n-van.UPF
ATOMIC_POSITIONS
Ga 0.00 0.00 0.00
As 0.25 0.25 0.25
K_POINTS {automatic}
4 4 4 0 0 0
EOF
$ECHO " running the scf calculation...c"
$PW_COMMAND < gaas.scf.in > gaas.scf.out
check_failure $?
$ECHO " done"
# DOS calculation for GaAs
cat > gaas.dos.in << EOF
&control
calculation='nscf'
prefix='gaas',
pseudo_dir = '$PSEUDO_DIR/',
outdir='$TMP_DIR/'
/
&system
ibrav=2, celldm(1) =10.68, nat=2, ntyp=2,
ecutwfc = 18.0, ecutrho = 1700.0, nbnd=10,
occupations='tetrahedra'
/
&electrons
conv_thr = 1.0e-10
mixing_beta = 0.7
/
ATOMIC_SPECIES
Ga 69.720 Ga.pbe-nsp-van.UPF
As 74.922 As.pbe-n-van.UPF
ATOMIC_POSITIONS
Ga 0.0 0.0 0.0
As 0.25 0.25 0.25
K_POINTS {automatic}
12 12 12 0 0 0
EOF
cat > gaas.dos2.in << EOF
&inputpp
outdir='$TMP_DIR/'
prefix='gaas'
fildos='gaas.dos',
Emin=-25.0, Emax=25.0, DeltaE=0.1
/
EOF
$ECHO " running DOS calculation for GaAs...c"
$PW_COMMAND < gaas.dos.in > gaas.dos.out
check_failure $?
$DOS_COMMAND < gaas.dos2.in > gaas.dos2.out
check_failure $?
$ECHO " done"
# phonon calculation on a (444) uniform grid of q-points
cat > gaas.ph.in << EOF
phonons of GaAs
&inputph
tr2_ph=1.0d-12,
prefix='gaas',
ldisp=.true.,
nq1=4, nq2=4, nq3=4
amass(1)=69.72,
amass(2)=74.92,
outdir='$TMP_DIR/',
fildyn='gaas.dyn',
/
EOF
$ECHO " running the phonon calculation ...c"
$PH_COMMAND < gaas.ph.in > gaas.ph.out
check_failure $?
$ECHO " done"
cat > q2r.in <<EOF
&input
fildyn='gaas.dyn', zasr='simple', flfrc='gaas444.fc'
/
EOF
$ECHO " transforming C(q) => C(R)...c"
$Q2R_COMMAND < q2r.in > q2r.out
check_failure $?
$ECHO " done"
cat > matdyn.in <<EOF
&input
asr='simple', amass(1)=69.72, amass(2)=74.922,
flfrc='gaas444.fc', flfrq='gaas.freq'
/
9
0.000 0.0 0.0 0.0
0.125 0.0 0.0 0.0
0.250 0.0 0.0 0.0
0.375 0.0 0.0 0.0
0.500 0.0 0.0 0.0
0.625 0.0 0.0 0.0
0.750 0.0 0.0 0.0
0.875 0.0 0.0 0.0
1.000 0.0 0.0 0.0
EOF
$ECHO " recalculating omega(q) from C(R)...c"
$MATDYN_COMMAND < matdyn.in > matdyn.out
check_failure $?
$ECHO " done"
cat > phdos.in <<EOF
&input
asr='simple', dos=.true. amass(1)=69.72, amass(2)=74.922,
flfrc='gaas444.fc', fldos='gaas.phdos', nk1=6,nk2=6,nk3=6
/
EOF
$ECHO " calculating phonon DOS ...c"
$MATDYN_COMMAND < phdos.in > phdos.out
check_failure $?
$ECHO " done"
$ECHO$ECHO "$EXAMPLE_DIR: done"***********************************************************NCPP***********************************************************
cat > gaas.scf.in << EOF
&control
calculation='scf'
restart_mode='from_scratch',
tstress = .true.
tprnfor = .true.
prefix='gaas',
pseudo_dir = '$PSEUDO_DIR/',
outdir='$TMP_DIR/'
/
&system
ibrav= 2, celldm(1) =10.68, nat= 2, ntyp= 2,
ecutwfc =60.0, ecutrho=450,
/
&electrons
conv_thr = 1.0d-8
mixing_beta = 0.7
/
ATOMIC_SPECIES
Ga 69.72 Ga.pz-bhs.UPF
As 74.92 As.gon.UPF
ATOMIC_POSITIONS
Ga 0.00 0.00 0.00
As 0.25 0.25 0.25
K_POINTS {automatic}
4 4 4 0 0 0
EOF
$ECHO " running the scf calculation...c"
$PW_COMMAND < gaas.scf.in > gaas.scf.out
check_failure $?
$ECHO " done"
# DOS calculation for GaAs
cat > gaas.dos.in << EOF
&control
calculation='nscf'
prefix='gaas',
pseudo_dir = '$PSEUDO_DIR/',
outdir='$TMP_DIR/'
/
&system
ibrav=2, celldm(1) =10.68, nat=2, ntyp=2,
ecutwfc = 60.0, ecutrho = 450.0, nbnd=10,
occupations='tetrahedra'
/
&electrons
conv_thr = 1.0e-10
mixing_beta = 0.7
/
ATOMIC_SPECIES
Ga 69.720 Ga.pz-bhs.UPF
As 74.922 As.gon.UPF
ATOMIC_POSITIONS
Ga 0.0 0.0 0.0
As 0.25 0.25 0.25
K_POINTS {automatic}
12 12 12 0 0 0
EOF
cat > gaas.dos2.in << EOF
&inputpp
outdir='$TMP_DIR/'
prefix='gaas'
fildos='gaas.dos',
Emin=-25.0, Emax=25.0, DeltaE=0.1
/
EOF
$ECHO " running DOS calculation for GaAs...c"
$PW_COMMAND < gaas.dos.in > gaas.dos.out
check_failure $?
$DOS_COMMAND < gaas.dos2.in > gaas.dos2.out
check_failure $?
$ECHO " done"
# phonon calculation on a (444) uniform grid of q-points
cat > gaas.ph.in << EOF
phonons of GaAs
&inputph
tr2_ph=1.0d-12,
prefix='gaas',
ldisp=.true.,
nq1=4, nq2=4, nq3=4
amass(1)=69.72,
amass(2)=74.92,
outdir='$TMP_DIR/',
fildyn='gaas.dyn',
/
EOF
$ECHO " running the phonon calculation ...c"
$PH_COMMAND < gaas.ph.in > gaas.ph.out
check_failure $?
$ECHO " done"
cat > q2r.in <<EOF
&input
fildyn='gaas.dyn', zasr='simple', flfrc='gaas444.fc'
/
EOF
$ECHO " transforming C(q) => C(R)...c"
$Q2R_COMMAND < q2r.in > q2r.out
check_failure $?
$ECHO " done"
cat > matdyn.in <<EOF
&input
asr='simple', amass(1)=69.72, amass(2)=74.922,
flfrc='gaas444.fc', flfrq='gaas.freq'
/
9
0.000 0.0 0.0 0.0
0.125 0.0 0.0 0.0
0.250 0.0 0.0 0.0
0.375 0.0 0.0 0.0
0.500 0.0 0.0 0.0
0.625 0.0 0.0 0.0
0.750 0.0 0.0 0.0
0.875 0.0 0.0 0.0
1.000 0.0 0.0 0.0
EOF
$ECHO " recalculating omega(q) from C(R)...c"
$MATDYN_COMMAND < matdyn.in > matdyn.out
check_failure $?
$ECHO " done"
cat > phdos.in <<EOF
&input
asr='simple', dos=.true. amass(1)=69.72, amass(2)=74.922,
flfrc='gaas444.fc', fldos='gaas.phdos', nk1=6,nk2=6,nk3=6
/
EOF
$ECHO " calculating phonon DOS ...c"
$MATDYN_COMMAND < phdos.in > phdos.out
check_failure $?
$ECHO " done"
$ECHO
$ECHO "$EXAMPLE_DIR: done"***********************************************************I will be highly thankful if one could please let me know the way out to this.Thank you.Shyam Lal GuptaIIT KanpurKanpurINDIA-208016.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.democritos.it/pipermail/pw_forum/attachments/20081110/393f81a9/attachment-0001.htm
More information about the Pw_forum
mailing list