[QE-users] I have failed to reproduce phonon DOS of germanium

[mkondrin]

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'
/

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