[QE-users] Query regarding vdW-DF2 functional

[Dhvaneel Visaria]

Hello users,

I have been trying to simulate graphene phonon dispersion using DFT-DF2 vdW
functional and ONCV pseudopotential.

I am using  input_dft=‘vdw-df2’. I am getting nice convergence with scf
calculations using pw.x but I am unable to achieve convergence despite all
adjustments to the numerical parameters (nmix_ph, alpha_mix, max_iter)
using ph.x. I have also recompiled QE after adjusting max_iter and ndim_mix
to allow max iterations beyond 100 and ndim_mix greater than 5 but to no
avail. I think that there could be an issue with the way I am trying to use
input_dft/PP for vdW-df2. Can someone point out the error?

The PP header and input to the pw.x & ph.x can be found at the end for
reference while the output files can be found in this link
<https://drive.google.com/drive/folders/1KVlLz6SoTpTdxcviNTyEvMAKrOJb1ZyM?usp=sharing>
-
https://drive.google.com/drive/folders/1KVlLz6SoTpTdxcviNTyEvMAKrOJb1ZyM?usp=sharing

Thank you very much.

Best Regards,
Dhvaneel Visaria
IIT Bombay
*Pseudopotential file:*
<UPF version="2.0.1">
  <PP_INFO>
    Generated using "atomic" code by A. Dal Corso  v.5.0.99 svn rev. 10869
    Author: TM
    Generation date: 10Apr2014
    Pseudopotential type: NC
    Element:  C
    Functional: REVPBE

*The input to the pw.x is as follows:*
 &control
  title='MyTitle'
  calculation='scf'
  restart_mode='from_scratch'
  outdir='/scratch/MatSim//dfpt_24_24_137407890'
  pseudo_dir='/home/MatSim/dhvaneel.visaria/VDW/graphene/df2/'
  prefix='dfpt_24_24_137407890'
  tprnfor=.true.
  tstress=.true.
 /

 &system
  ibrav=0
  nat=2
  ntyp=1
  ecutwfc=100.00
  occupations='smearing'
  smearing='gaussian'
  degauss=0.01
  input_dft='vdw-df2'
 /

 &electrons
  conv_thr=1.0d-12
  mixing_beta=0.1
 /

 &IONS

 /

 &CELL
 /

 ATOMIC_SPECIES
  C  12.01 C.UPF


 ATOMIC_POSITIONS angstrom
  C  0.0000000000 0.0000000000 0.0000000000
  C  1.2370000000 0.7141822830 0.0000000000


 K_POINTS automatic
  12 12 1 0 0 0


 CELL_PARAMETERS Angstrom
  1.2370000000 -2.1425468490 0.0000000000
  1.2370000000 2.1425468490 0.0000000000
  0.0000000000 0.0000000000 12.0000000000
*The input to ph.x is as follows:*
 title='MyTitle'
 &inputph
  tr2_ph=1.0d-18
  niter_ph=200
  nmix_ph=8
  alpha_mix(1)=0.3
  ldisp=.true.
  search_sym=.true.
  trans=.true.
  nq1=24
  nq2=24
  nq3=1
  prefix='dfpt_24_24_137407890'
  fildyn='dfpt.dyn'
  outdir='/scratch/MatSim//dfpt_24_24_137407890'
 /
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20200921/8e45016f/attachment.html>