[QE-users] About Phonon calculations, is it possible to calculater lraman (Raman) without calculating the the repentation Self-consistent Calculation again, it is a lot of cost.

[Ramesh Kumar Kamadurai]

Yes you can start phonon calculation with different sets of parameters
using the same *wfc file. It is not necessary to redo scf calculation. But
recover=.true (Phonon recovery) option may not be possible for this case
because you intend to change the parameter for your new calculation. Hope
this helps.

Best regards,

K. Ramesh Kumar

 Assistant Professor

Gandhi Institute of Technology and Management,

 Phone: +91 9895637981, +1 6782419790

Email: kraamesh57 at gmail.com rkamadur at gitam.edu

On Mon, Oct 30, 2023 at 12:14 PM ludwigboltzmann.sc10 at nycu.edu.tw <
ludwigboltzmann.sc10 at nycu.edu.tw> wrote:

> Dear users:
>
> I am going to calculate do phonon calculation and Raman spectra
> calculation of my perovskite(only at Gamma point),
>
> My procedure is like this: doint: vc-relax & scf→phonon calculation→dynmat
>
> #phonon
> phonon calculation for diamondg(Only gamma pt).  !use QEsub_ph (ph.x)
> (rather than pw.x)
> &inputph
>   outdir="output"
>   prefix = ' perovskite',
>   tr2_ph = 1.0d-14               !Threshold for self-consistency
>   ldisp = .false
>   asr = .true
>   zue = .true
>   epsil = .true
>   trans = .true
>   fildyn = ' perovskite.dyn'
>   start_q = 1
>   last_q = 1
>   "lraman = .true."
>   recover = .true !start from old
> /
> 0 0 0                            !gamma pt
>
> I made a mistake without adding  "lraman = .true.", so I got dynmat.out
> with only IR but without Raman activities.
> Is it possible to calculater lraman (Raman) without calculating the
> repentation Self-consistent Calculation  again, it is a lot of cost.
>
> Representation #   1 mode #   1
>
>      Self-consistent Calculation
>
>       iter #   1 total cpu time : 21284.5 secs   av.it.:   5.0
>       thresh= 1.000E-02 alpha_mix =  0.700 |ddv_scf|^2 =  6.481E-09
>
>       iter #   2 total cpu time : 21666.4 secs   av.it.:  17.0
>       thresh= 8.051E-06 alpha_mix =  0.700 |ddv_scf|^2 =  1.068E-08
>
>       iter #   3 total cpu time : 22023.4 secs   av.it.:  16.0
>       thresh= 1.033E-05 alpha_mix =  0.700 |ddv_scf|^2 =  3.855E-10
>
>       iter #   4 total cpu time : 22379.9 secs   av.it.:  16.0
>       thresh= 1.963E-06 alpha_mix =  0.700 |ddv_scf|^2 =  1.560E-11
>
>       iter #   5 total cpu time : 22749.5 secs   av.it.:  16.9
>       thresh= 3.950E-07 alpha_mix =  0.700 |ddv_scf|^2 =  1.517E-12
>
>       iter #   6 total cpu time : 23124.2 secs   av.it.:  17.0
>       thresh= 1.232E-07 alpha_mix =  0.700 |ddv_scf|^2 =  1.771E-13
>
>       iter #   7 total cpu time : 23504.1 secs   av.it.:  17.0
>       thresh= 4.208E-08 alpha_mix =  0.700 |ddv_scf|^2 =  2.903E-14
>
>       iter #   8 total cpu time : 23890.4 secs   av.it.:  17.9
>       thresh= 1.704E-08 alpha_mix =  0.700 |ddv_scf|^2 =  1.027E-14
>
>       iter #   9 total cpu time : 24267.0 secs   av.it.:  17.0
>       thresh= 1.013E-08 alpha_mix =  0.700 |ddv_scf|^2 =  5.001E-15
>
>      End of self-consistent calculation
>
>      Convergence has been achieved
>
>
> Sincerely,
>
> National Yang Ming Chiao Tung University
> HY Lu
>
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