[QE-users] phonon linewidth calculation

[Ivan Dario Arellano Ramirez]

I QE users

I want to calculate the phonon linewidth for InN. I am following two
tutorials. However, in both cases, I encounter the same issue: no
convergence when using the ph.x module.

Pert. #  1: Fermi energy shift (Ry) =    -5.5393E+02     0.0000E+00

      iter # 150 total cpu time : 13815.8 secs   av.it.:   5.3
      thresh= 4.679E-04 alpha_mix =  0.700 |ddv_scf|^2 =  4.318E-06

     End of self-consistent calculation

     No convergence has been achieved


This is an overview of the two approaches I followed:

1) perform very dense scf calculation with la2F=.true. in &systems (Likely,
I am exceeding the maximum of 40000 k points)
2) normal scf on coarser k-mesh
3) phonon calculation using ph.x
4) Inverse Fourier transform of dynamical matrix and the phonon linewidth
using q2r.x
5) Fourier transform to obtain dynamical matrix and the phonon linewidth
using matdyn.x

The other tutorial proposed an initial scf calculation followed by an nscf
calculation with la2F=.true. the rest of steps are the same.

Here are all the inputs.

Any suggestions or insights would be greatly appreciated.


1) very dense k-mesh scf

&control
    calculation = 'scf'
    restart_mode='from_scratch',
    prefix='inn_ep',
    tstress = .true.
    tprnfor = .true.
    pseudo_dir = '/home/pps/pbe.0.3.1/PSEUDOPOTENTIALS/',
    outdir='./tmp'
    verbosity = 'high'
    etot_conv_thr = 1.d-6
    forc_conv_thr = 1.d-5
/
&system
    ibrav = 0,
    nat=  4,
    ntyp= 2,
    ecutwfc = 90,
    ecutrho = 900,
    occupations='smearing',
    smearing='m-v',
    degauss=0.02,
    la2F = .true.
/
&electrons
    conv_thr =  1.0d-8
    electron_maxstep = 200,
    mixing_mode = 'plain'
    mixing_beta = 0.3D0
    diagonalization  = 'david'
 /
ATOMIC_SPECIES
In   114.818    In.pbe-dn-rrkjus_psl.1.0.0.UPF
N   14.007      N.pbe-n-rrkjus_psl.1.0.0.UPF
CELL_PARAMETERS angstrom
   1.793358573  -3.106188164   0.000000000
   1.793358573   3.106188164   0.000000000
   0.000000000   0.000000000   5.799337066

ATOMIC_POSITIONS crystal
In            0.3333330000        0.6666670000       -0.0019331848
In            0.6666670000        0.3333330000        0.4980668152
N             0.3333330000        0.6666670000        0.3767331848
N             0.6666670000        0.3333330000        0.8767331848
K_POINTS automatic
45 45 36 0 0 0

2) normal scf

&control
    calculation = 'scf'
    restart_mode='from_scratch',
    prefix='inn_ep',
    tstress = .true.
    tprnfor = .true.
    pseudo_dir = '/home/pps/pbe.0.3.1/PSEUDOPOTENTIALS/',
    outdir='./tmp'
    verbosity = 'high'
    etot_conv_thr = 1.d-6
    forc_conv_thr = 1.d-5
/
&system
    ibrav = 0,
    nat=  4,
    ntyp= 2,
    ecutwfc = 90,
    ecutrho = 900,
    occupations='smearing',
    smearing='m-v',
    degauss=0.02,
/
&electrons
    conv_thr =  1.0d-8
    electron_maxstep = 200,
    mixing_mode = 'plain'
    mixing_beta = 0.3D0
    diagonalization  = 'david'
 /
ATOMIC_SPECIES
In   114.818    In.pbe-dn-rrkjus_psl.1.0.0.UPF
N   14.007      N.pbe-n-rrkjus_psl.1.0.0.UPF
CELL_PARAMETERS angstrom
   1.793358573  -3.106188164   0.000000000
   1.793358573   3.106188164   0.000000000
   0.000000000   0.000000000   5.799337066

ATOMIC_POSITIONS crystal
In            0.3333330000        0.6666670000       -0.0019331848
In            0.6666670000        0.3333330000        0.4980668152
N             0.3333330000        0.6666670000        0.3767331848
N             0.6666670000        0.3333330000        0.8767331848
K_POINTS automatic
15 15 12 0 0 0

3) phonon calculation

Phonons of InN at G!=0
&inputph
 tr2_ph = 1.0d-14,
 ldisp = .true.,
 prefix = 'inn_ep',
 recover = .true.
 fildyn = 'inn-ph.dyn',
 fildvscf = 'inndv'
 nq1 = 5,
 nq2 = 5,
 nq3 = 3,
 electron_phonon = 'interpolated'
 el_ph_nsigma = 10
 el_ph_sigma = 0.02
 amass(1) = 114.818,
 amass(2) = 14.007,
 outdir =  './tmp'
 /

 4) Inverse Fourier Transform

&INPUT
 fildyn = 'inn-ph.dyn',
 zasr = 'crystal',
 flfrc =  'inn-ph.fc',
 la2F = .true.
 /

5) Fourier Transform

&input
 asr = 'crystal',
 flfrc = 'inn-ph.fc',
 flfrq = 'inn.band.freq'
 flvec = 'inn.band.modes'
 amass(1) = 114.818,
 amass(2) = 14.007,
 q_in_band_form = .true.
 la2F = .true.
 /
8
   0.0000000000     0.0000000000     0.0000000000  40  ! Gamma
   0.5000000000     0.0000000000     0.0000000000  25  ! M
   0.3333333333     0.3333333333     0.0000000000  40  ! K
   0.0000000000     0.0000000000     0.0000000000  25  ! Gamma
   0.0000000000     0.0000000000     0.5000000000  40  ! A
   0.5000000000     0.0000000000     0.5000000000  25  ! L
   0.3333333333     0.3333333333     0.5000000000  40  ! H
   0.0000000000     0.0000000000     0.5000000000  1   ! A


Best regards,

-- 

Iván Darío Arellano Ramírez

Profesor Titular Programa de Ingeniería Física

Director Grupo de Investigación en Modelado y Simulación Computacional

Universidad Tecnológica de Pereira

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