[QE-developers] Problem in ph.x and epw.x (Wrong classes for C_3v) -

[Gopalan, Sanjay]

Dear all,


I have been trying to calculate el-ph coupling constant for monolayer MoTe2 using QE and EPW.


While calculating the phonon energies using ph.x I get error as


     task #         3
     from divide_class : error #         1
     Wrong classes for C_3v

But when I add the tag search_sym=.FALSE. as directed in this https://lists.quantum-espresso.org/pipermail/users/2017-August/039055.html, I am able to calculate the phonon energies.

But, when I try to calculate el-ph coupling constant using EPW, I get the same error. Is there any way to switch off symmetry in EPW or other ways to overcome this error in ph.x?

My scf input file

&CONTROL
  calculation='scf',
  outdir='./',
  prefix='calc',
  pseudo_dir='./',
  verbosity='low',
  wf_collect= .true.
/

&SYSTEM

    ibrav=0,
    nat= 3, ntyp= 2, nbnd= 27,
    ecutwfc = 60, ecutrho=240,
    occupations = 'fixed'

/

&ELECTRONS
  conv_thr=1d-9,
  mixing_beta=0.7d0,
/
ATOMIC_SPECIES

  Mo 95.96 Mo_ONCV_PBE_sr.upf
  Te 127.6 Te_ONCV_PBE_sr.upf

ATOMIC_POSITIONS (crystal)
Mo       0.333333015000d0   0.333333015000d0   0.154510160000d0
Te       0.666666985000d0   0.666666985000d0   0.226882756000d0
Te       0.666666985000d0   0.666666985000d0   0.082149790000d0

K_POINTS {automatic}
  12 12 1 0 0 0

CELL_PARAMETERS (angstrom)
   1.779701562000d0   3.082533129000d0   0.000000000000d0
  -1.779701562000d0   3.082533129000d0   0.000000000000d0
   0.000000000000d0   0.000000000000d0  25.000000000000d0

and ph.x input file

MoTe2_phonon
 &inputph
  recover=.true.,
  tr2_ph=1.0d-16,
  prefix='calc',
  fildvscf='dvscf',
  amass(1)=95.960d0
  amass(2)=127.60d0
  outdir='./',
  ldisp=.true.,
  nq1=6,nq2=6,nq3=1,
  fildyn='calc.dyn',
 search_sym=.FALSE.
 /

Thank you
Sanjay Gopalan
Research Assistant
University of Texas at Dallas



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