[Pw_forum] Phonon calculation
Vincenzo Verdolino
vincenzo.verdolino at gmail.com
Mon Aug 25 07:25:33 CEST 2014
Dear QE community,
I am dealing with phonon calculations on ferromagnetic bcc iron. I am trying to reproduce results published by Dal Corso and Gironcoli on Phys Rew B 62 (1) 2000. I did several testing including K-points sampling, kinetic cut off and augmented charges, LDA and BPE potentials etc... Here it follows 1)the vc-relaxation input, 2)the scf single point on the optimized structure, 3) the phonon calculation input file, 4) the q2r input file, 5) the matdyn inputfile. Attached you will find a pdf reporting the obtained phonon dispersion. As you can see around GAMMA i've got anoing soft mode with immaginary frequencies. I do have the same results both with LDA and PBE PP. Could any of you kindly check if 1)my pw.x input conditions are the same reported by Dal Corso and 2) do you have any idea why this system seems to be unstable along that direction? I suspect that's something with magnetic microstates or so...Just want to finally point out that I have same issues calculatin phonon at a given q vector (around GAMMA with no- furier interpolation) and also employing experimental lattice parameter. One more hint, my vc-relaxation converges to a=5.38 u.a. instead of 5.42 u.a. as published and residual bulk pressure 0.1-0.01 kbar
&control
pseudo_dir = '/users/verdoliv/espresso/pseudo/IronPseudo/',
outdir='./',
prefix='iron_PBEexp',
restart_mode='restart',
title='phonongamma-scf',
calculation='vc-relax',
ndw = 56,
/
&system
ibrav= 3, celldm(1)=5.41,
nat=1, ntyp=1,
ecutwfc=25.0, ecutrho=400.0,
occupations='smearing', smearing='mv', degauss=0.01,
nbnd=10,
nspin=2,
starting_magnetization(1)=0.6,
/
&electrons
mixing_beta = 0.5,
conv_thr = 1.0d-10,
/
&IONS
/
&CELL
cell_dynamics='bfgs',
press_conv_thr=0.05D0,
/
ATOMIC_SPECIES
Fe 55.845 Fe.pbe-nd-rrkjus.UPF
ATOMIC_POSITIONS
Fe 0.000000 0.000000 0.000000
K_POINTS automatic
16 16 16 0 0 0
---------------------------------------------------------------
&control
pseudo_dir = '/users/verdoliv/espresso/pseudo/IronPseudo/',
outdir='./',
prefix='iron_PBEexp',
restart_mode='from_scratch',
tstress = .true.,
tprnfor = .true.,
calculation='scf',
ndw = 56,
wf_collect=.TRUE.,
/
&system
ibrav= 3, celldm(1)=5.3770438288,
nat=1, ntyp=1,
ecutwfc=25.0, ecutrho=400.0,
occupations='smearing', smearing='mv', degauss=0.01,
nbnd=10,
nspin=2,
starting_magnetization(1)=0.6,
/
&electrons
startingwfc='atomic',
mixing_beta = 0.5,
mixing_mode='local-TF',
conv_thr = 1.0d-10,
/
&IONS
/
&CELL
/
ATOMIC_SPECIES
Fe 55.845 Fe.pbe-nd-rrkjus.UPF
ATOMIC_POSITIONS
Fe 0.000000 0.000000 0.000000
K_POINTS automatic
16 16 16 0 0 0
--------------------------
ph.x input
phonons of Vinny's Iron
&inputph
tr2_ph=1.0d-14,
prefix='iron_PBEexp_16x16x16',
ldisp=.true.,
nq1=4, nq2=4, nq3=4,
amass(1)=55.845,
outdir='/mnt/lnec/verdoliv/AMMONIA/MONCH-LAST/PHONON/output/ph4_PBEexp_16x16x16/'
epsil=.false.,
fildyn='iron_ph4_PBEexp_16x16x16.dyn',
/
-------------------------------------------------------------
q2r.x input
&input
zasr='simple', fildyn='iron_ph4_PBEexp.dyn', flfrc='iron_ph4_PBEexp.fc',
/
matdyn.x input
&input
asr='simple', amass(1)=55.845,
flfrc='iron_ph4_PBEexp_16x16x16.fc', flfrq='ironNtoGAMMA_PBEexp_16x16x16.freq'
/
100
0.495 0.495 0.000 0.000
0.490 0.490 0.000 0.000
0.485 0.485 0.000 0.000
0.480 0.480 0.000 0.000
0.475 0.475 0.000 0.000
0.470 0.470 0.000 0.000
0.465 0.465 0.000 0.000
0.460 0.460 0.000 0.000
0.455 0.455 0.000 0.000
0.450 0.450 0.000 0.000
0.445 0.445 0.000 0.000
0.440 0.440 0.000 0.000
0.435 0.435 0.000 0.000
0.430 0.430 0.000 0.000
0.425 0.425 0.000 0.000
0.420 0.420 0.000 0.000
0.415 0.415 0.000 0.000
0.410 0.410 0.000 0.000
0.405 0.405 0.000 0.000
0.400 0.400 0.000 0.000
0.395 0.395 0.000 0.000
0.390 0.390 0.000 0.000
0.385 0.385 0.000 0.000
0.380 0.380 0.000 0.000
0.375 0.375 0.000 0.000
0.370 0.370 0.000 0.000
0.365 0.365 0.000 0.000
0.360 0.360 0.000 0.000
0.355 0.355 0.000 0.000
0.350 0.350 0.000 0.000
0.345 0.345 0.000 0.000
0.340 0.340 0.000 0.000
0.335 0.335 0.000 0.000
0.330 0.330 0.000 0.000
0.325 0.325 0.000 0.000
0.320 0.320 0.000 0.000
0.315 0.315 0.000 0.000
0.310 0.310 0.000 0.000
0.305 0.305 0.000 0.000
0.300 0.300 0.000 0.000
0.295 0.295 0.000 0.000
0.290 0.290 0.000 0.000
0.285 0.285 0.000 0.000
0.280 0.280 0.000 0.000
0.275 0.275 0.000 0.000
0.270 0.270 0.000 0.000
0.265 0.265 0.000 0.000
0.260 0.260 0.000 0.000
0.255 0.255 0.000 0.000
0.250 0.250 0.000 0.000
0.245 0.245 0.000 0.000
0.240 0.240 0.000 0.000
0.235 0.235 0.000 0.000
0.230 0.230 0.000 0.000
0.225 0.225 0.000 0.000
0.220 0.220 0.000 0.000
0.215 0.215 0.000 0.000
0.210 0.210 0.000 0.000
0.205 0.205 0.000 0.000
0.200 0.200 0.000 0.000
0.195 0.195 0.000 0.000
0.190 0.190 0.000 0.000
0.185 0.185 0.000 0.000
0.180 0.180 0.000 0.000
0.175 0.175 0.000 0.000
0.170 0.170 0.000 0.000
0.165 0.165 0.000 0.000
0.160 0.160 0.000 0.000
0.155 0.155 0.000 0.000
0.150 0.150 0.000 0.000
0.145 0.145 0.000 0.000
0.140 0.140 0.000 0.000
0.135 0.135 0.000 0.000
0.130 0.130 0.000 0.000
0.125 0.125 0.000 0.000
0.120 0.120 0.000 0.000
0.115 0.115 0.000 0.000
0.110 0.110 0.000 0.000
0.105 0.105 0.000 0.000
0.100 0.100 0.000 0.000
0.095 0.095 0.000 0.000
0.090 0.090 0.000 0.000
0.085 0.085 0.000 0.000
0.080 0.080 0.000 0.000
0.075 0.075 0.000 0.000
0.070 0.070 0.000 0.000
0.065 0.065 0.000 0.000
0.060 0.060 0.000 0.000
0.055 0.055 0.000 0.000
0.050 0.050 0.000 0.000
0.045 0.045 0.000 0.000
0.040 0.040 0.000 0.000
0.035 0.035 0.000 0.000
0.030 0.030 0.000 0.000
0.025 0.025 0.000 0.000
0.020 0.020 0.000 0.000
0.015 0.015 0.000 0.000
0.010 0.010 0.000 0.000
0.005 0.005 0.000 0.000
-0.000 -0.000 0.000 0.000
------------------------------------------
---------------------------
THank you in advance
Sent from my iPhone
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