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

[Paolo Giannozzi]

If you are using v.7.4.1 and later, please see this:
    https://gitlab.com/QEF/q-e/-/merge_requests/2715
Paolo

On 11/5/2025 4:27 PM, Shubham Patel via users wrote:
> 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
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216