[Pw_forum] Raman

[Ilya Ryabinkin]

In a nutshell: you have been told: "third-order derivatives are not
implemented".

Long answer: Raman intensities are proportional to the first
derivatives of polarisabilities wrt nuclear displacements;
polarizabilities, in turn, are the second derivatives of energy wrt to
electric field components. In total, we end up with third, albeit
mixed, derivatives.

--
I.

On Tue, Dec 8, 2015 at 6:25 PM, Mofrad, Amir Mehdi (MU-Student)
<amzf5 at mail.missouri.edu> wrote:
> Dear Quantum Espresso users and developers,
>
>
> Does anyone know that Quantum Espresso is capable of calculating Raman
> intensities? When I want to do the phonon calculations I get the following
> error:
>
>
> error: task #         0
>      from phq_setup : error #         1
>      third order derivatives not implemented with GGA
>
> According to what is provided on the Quantum Espresso website, Raman
> calculations work only with NC pseudo-potentials and I tried to use that
> kind of PP in my scf calculations. Below is my scf and phonon calculations
> input files. Any help would be thoroughly appreciated on how to get Raman
> intensities.
>
>
> SCF INPUT:
>
>  &CONTROL
>  calculation = 'scf' ,
>  restart_mode = 'from_scratch' ,
>  wf_collect = .true. ,
>  outdir = './scratch' ,
>  wfcdir = './scratch' ,
>  pseudo_dir = '/global/espresso/pseudo' ,
>  prefix = 'SOD' ,
>  verbosity = 'high' ,
>  etot_conv_thr = 1e-5 ,
>  forc_conv_thr = 1e-4 ,
>  nstep = 50 ,
>  tstress = .true. ,
>  tprnfor = .true. ,
>
>  /
>
>  &SYSTEM
>  ibrav = 0,
>  nat = 36,
>  ntyp = 2,
>  ecutwfc = 50 ,
>  ecutrho = 200 ,
>
> /
>
>  &ELECTRONS
>   electron_maxstep = 100,
>   conv_thr = 3e-8 ,
>   mixing_mode = 'plain' ,
>   mixing_beta = 0.7 ,
>   diagonalization = 'david' ,
>
> /
> CELL_PARAMETERS bohr
>  16.720296750    0.000000000    0.000000000
>  0.000000000   16.720296750    0.000000000
>  0.000000000    0.000000000   16.720296750
> ATOMIC_SPECIES
>    Si   28.08600  Si.tpss-mt.UPF
>     O   15.99940  O.tpss-mt.UPF
> ATOMIC_POSITIONS angstrom
>  Si      2.211434087    0.000000000    4.424000000
>    Si      6.636565913    0.000000000    4.424000000
>    Si      4.424000000    2.211434087    0.000000000
>    Si      4.424000000    6.636565913    0.000000000
>    Si      0.000000000    4.424000000    2.211434087
>    Si      0.000000000    4.424000000    6.636565913
>    Si      2.211424138    4.424000000   -0.000000000
>    Si      6.636575862    4.424000000   -0.000000000
>    Si      0.000000000    2.211424138    4.424000000
>    Si      0.000000000    6.636575862    4.424000000
>    Si      4.424000000    0.000000000    2.211424138
>    Si      4.424000000    0.000000000    6.636575862
>     O      1.287284142    4.077513340    1.287298380
>     O      7.560715858    4.770486660    1.287298380
>     O      7.560715858    4.077513340    7.560701620
>     O      1.287284142    4.770486660    7.560701620
>     O      1.287298380    1.287284142    4.077513340
>     O      1.287298380    7.560715858    4.770486660
>     O      7.560701620    7.560715858    4.077513340
>     O      7.560701620    1.287284142    4.770486660
>     O      4.077513340    1.287298380    1.287284142
>     O      4.770486660    1.287298380    7.560715858
>     O      4.077513340    7.560701620    7.560715858
>     O      4.770486660    7.560701620    1.287284142
>     O      8.506650498    5.713870775    5.713853509
>     O      0.341349502    3.134129225    5.713853509
>     O      8.506650498    3.134129225    3.134146491
>     O      0.341349502    5.713870775    3.134146491
>     O      5.713870775    5.713853509    8.506650498
>     O      3.134129225    5.713853509    0.341349502
>     O      3.134129225    3.134146491    8.506650498
>     O      5.713870775    3.134146491    0.341349502
>     O      5.713853509    8.506650498    5.713870775
>     O      5.713853509    0.341349502    3.134129225
>     O      3.134146491    8.506650498    3.134129225
>     O      3.134146491    0.341349502    5.713870775
> K_POINTS automatic
> 4 4 4   1 1 1
>
> Phonon Input File
>
>
> phonons of Sodalite at Gamma
> &inputph
>     tr2_ph            = 1e-14,
>     prefix            = 'SOD',
>     amass(1)          =  28.08600,
>     amass(2)          =  15.9940,
>     outdir            = './scratch/',
>     fildyn            = 'SOD.dyn',
>     recover           = .false.,
>     epsil             = .true.,
>     lraman            = .true.,
>     trans             = .true.,
>     max_seconds       = 350000
> /
> 0.0 0.0 0.0
>
> Best regards,
>
>
> Amir M. Mofrad
>
> University of Missouri
>
>
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-- 
*******************************************************
                    Ilya Ryabinkin
                 Postdoctoral Scholar
          Physical and Environmental Sciences
           University of Toronto Scarborough
  http://www.utsc.utoronto.ca/~aizmaylov/Members.html
*******************************************************