Dear QE developers and users!I am at a loss. I have tried to reproduce phonon density of state using Quantum ESPRESSO and various pseudopotentials and functionals but can not model the experimental PDOS. I have tried LDA and GGA functionals (see attached figure) but the largest frequency is not larger than 265 cm-1 (in comparison to the experimental Raman one equal to 300 cm-1). Obviously I have missed something, but can not figure where. Any suggestions would be highly appreciated.
SCF and PH calculations files are included below. PNG figure with PDOS (where experimental PDOS is marked with symbols) is attached to the email.
Sincerely yours,
M.V. Kondrin
>>scf.in>>
&control
title='SCF for phonon Ge',
calculation='scf',
prefix='ge.ph0',
tstress=.true.,
tprnfor=.true.,
disk_io='low',
pseudo_dir = '/home/mike/QE/pseudo/',
outdir='./tmp'
/
&SYSTEM
ibrav = 0
A = 5.658
nat = 2
ntyp = 1
tot_charge=0,
ecutwfc=70,
occupations='smearing',
smearing='methfessel-paxton',
degauss=0.02
/
&electrons
mixing_beta = 0.7,
conv_thr = 1.0d-5
/
&ions
/
&cell
cell_factor=4,
press=0.0
/
ATOMIC_SPECIES
Ge 72.63000 Ge.pz-bhs.UPF
CELL_PARAMETERS (alat= 10.69207046)
-0.510237966 0.000000000 0.510237966
-0.000000000 0.510237966 0.510237966
-0.510237966 0.510237966 0.000000000
K_POINTS {automatic}
8 8 8 0 0 0
ATOMIC_POSITIONS {crystal}
Ge 0.000000000000000 0.000000000000000 0.000000000000000
Ge 0.250000000000000 0.250000000000000 0.250000000000000
>>ph.in>>
Phonons_in_germanium_at_4x4x4_grid
&inputph
tr2_ph=1.0d-14,
ldisp=.true.,
nq1=4,
nq2=4,
nq3=4,
amass(1)=72.63000,
prefix='ge.ph0',
recover=.false.,
outdir='./tmp',
fildyn='ge-grid-ph.dyn'
/
RPlots.pdf
Description: Adobe PDF document
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