[QE-users] Raman spectra with GGA

[Ari P Seitsonen]

Dear Karolina, Giuseppe et co,

   Indeed the "standard solution" has been to switch off the test and 
continue the calculation, yielding the intensities calculated with LDA 
(the frequencies are consistent with the ground-state calculation, GGA 
that is). Just last week I discussed with one Developer of the 
PHonon/Raman codes, who mentioned he had basically implemented also the 
third order derivatives, but they are not yet included in the 
distribution.

-----------------------------------------------------------------------------
#$ grep -n -B 1 apsi /sw/source/intel/app/qe/qe-6.3/PHonon/PH/phq_setup.f90
123-     'third order derivatives not implemented with GGA', 0)
124:!apsi     'third order derivatives not implemented with GGA', 1)
-----------------------------------------------------------------------------

This tells the code to write out the warning but continue, whereas the 
original code stops with the same (error) message.

     Greetings from Sunny Paris,

        apsi

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   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
     Ecole Normale Supérieure (ENS), Département de Chimie, Paris
     Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Thu, 4 Oct 2018, Giuseppe Mattioli wrote:

>
> Dear Karolina
>
> AFAIK gradient corrections have been never "officially" implemented in ph.x 
> RAMAN calculations and you are stuck at LDA level. I saw Ari Seitsonen's 
> slides you mention (I suppose), and in the last slide there is actually this 
> caveat
>
> Limitations: Beyond LDA only with shortcuts
>
> If you want to know such shortcuts you should ask Ari, or the Authhors of the 
> graphene nanoribbon paper (if you find it, because it is not cited in the 
> slides).
>
> HTH
> Giuseppe
>
> Karolina Milowska <karolina.milowska at gmail.com> ha scritto:
>
>> Dear All,
>> 
>> Recently, I have came across files and slides from MASTANI Summer School
>> from 2014, in particular - the calculation of Raman spectrum of graphene
>> nanoribbon. I would like to reproduce this example. Unfortunately, version
>> 6.3 doesn't allow me to do that.
>> 
>> This is he error message:
>> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>>     Error in routine phq_setup (1):
>>     third order derivatives not implemented with GGA
>> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>> 
>> May I ask you where can I find the version of qe which has this
>> implementation?
>> 
>> Kind regards,
>> Karolina
>
>
>
> GIUSEPPE MATTIOLI
> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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> E-mail: <giuseppe.mattioli at ism.cnr.it>
>
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