[QE-users] Raman spectra for metallic system in QE

[Shubham Patel]

Dear Quantum Espresso users,

I am doing phonon calculations to calculate the dielectric constant and Raman spectra, but in the output I am getting the dielectric constant in form of '*****', is it because the value is too large?
More specifically, is it true that calculating Raman spectra for metals is not implemented in Quantum Espresso. How does that work in VASP (for metals)?

###########################################

iter #  30 total cpu time :   130.1 secs   av.it.:  21.3
      thresh= 6.211E-10 alpha_mix =  0.700 |ddv_scf|^2 =  1.347E-18

      iter #  31 total cpu time :   134.9 secs   av.it.:  22.7
      thresh= 1.161E-10 alpha_mix =  0.700 |ddv_scf|^2 =  5.013E-19

     End of electric fields calculation

          Dielectric constant in cartesian axis

          (******************      -0.381280124       0.000000000 )
          (       0.381280154******************       0.000000000 )
          (       0.000000000       0.000000000    -284.777139614 )
##########################################################

Also, there is this scf cycle for dv_scf, the value of which is keep increasing.

#######################################################

Derivative coefficient:  0.001000    Threshold: 1.00E-12
     kpoint   1 ibnd**** pcgreen: root not converged 2.723E-08
     kpoint   1 ibnd**** pcgreen: root not converged 2.007E-09
     kpoint   1 ibnd**** pcgreen: root not converged 8.698E-09
     kpoint   1 ibnd**** pcgreen: root not converged 9.726E-11
     kpoint   1 ibnd**** pcgreen: root not converged 5.332E-11
     kpoint   1 ibnd**** pcgreen: root not converged 1.593E-12
     kpoint   1 ibnd**** pcgreen: root not converged 1.676E-12
     kpoint   1 ibnd**** pcgreen: root not converged 1.638E-12
     kpoint   1 ibnd**** pcgreen: root not converged 1.803E-12
     Non-scf  u_k: avg # of iterations = 33.0
     Non-scf Du_k: avg # of iterations = 71.8

          Dielectric constant from finite-differences

          (******************      -0.000005722       0.000000000 )
          (      -0.000003815******************       0.000000000 )
          (      -0.000000000      -0.000000000  -31779.441608902 )

     Computing Second order response
     kpoint   1 ibnd**** pcgreen: root not converged 3.031E+01
     kpoint   1 ibnd**** pcgreen: root not converged 6.080E+01
     kpoint   1 ibnd**** pcgreen: root not converged 6.610E+01


      iter #   1   av.it.:  65.3
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  1.221E+30
     kpoint   1 ibnd**** pcgreen: root not converged 2.161E+07
     kpoint   1 ibnd**** pcgreen: root not converged 2.800E+06
     kpoint   1 ibnd**** pcgreen: root not converged 9.143E+06


      iter #   2   av.it.:  82.3
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  2.786E+39
     kpoint   1 ibnd**** pcgreen: root not converged 2.487E+08
     kpoint   1 ibnd**** pcgreen: root not converged 1.773E+10
     kpoint   1 ibnd**** pcgreen: root not converged 1.710E+09


      iter #   3   av.it.:  74.0
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  6.365E+40
     kpoint   1 ibnd**** pcgreen: root not converged 2.377E+08
     kpoint   1 ibnd**** pcgreen: root not converged 1.246E+08
     kpoint   1 ibnd**** pcgreen: root not converged 1.434E+08


      iter #   4   av.it.:  89.0
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  4.085E+41
     kpoint   1 ibnd**** pcgreen: root not converged 6.110E+07
     kpoint   1 ibnd**** pcgreen: root not converged 4.883E+08
     kpoint   1 ibnd**** pcgreen: root not converged 5.098E+07


      iter #   5   av.it.:  81.7
      thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  3.790E+41
...

################################################

Here is my input for the ph.x

&inputph
  tr2_ph=1.0d-18,
  prefix='conbse',
  amass(2)= 92.90638,
  amass(3)= 78.96,
  outdir='./out/',
  fildyn='conbse.dynG',
  lraman=.true.,
  epsil=.true.,
  trans=.true.,
  asr=.true.
 /
0.0 0.0 0.0

Could somebody tell me why this cycle for dv_scf which increases infinitely? I am doing a Gamma point calculation for pw.x and ph.x.

Thank you for your time.

Sincerely,
Shubham