[Pw_forum] Reproduce Raman simulation of Graphene nanoribbon using QE

[Ari P Seitsonen]

Dear Takahiro Nakae,

   I guess I should give an answer, given that I produced the spectrum in 
the article referred in your mail and the exercises to that course.

   The methods for calculating the Raman intensity of the different phonons 
is not consistent between the article and the exercises: In the former we 
used a separate program in which we could choose the wave vectors of the 
incoming and scattered light, whereas in the latter a spherical average 
(to my knowledge) is performed.

   We are working on publishing the code which would enable doing more 
sophisticated analysis of the Raman spectra.

     Greetings,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   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 Fri, 23 Jan 2015, Takahiro Nakae wrote:

> Dear All,
>
> I am trying to calculate Raman spectra of graphene nanoribbon. At the
> first step, I am trying to reproduce the result reported in Nature 2010,
> 466, 470-473 by J Cai et al.(DOI:10.1038/nature09211).
>
> I found a tutorial documents and examples of MASTANI2014 on the internet .
> http://www.iiserpune.ac.in/~smr2626/talks-presentations.html
> At the 11th July session, Raman-IR example files are provided.
>
> On this calculation, Raman signal intensity were not consistent as
> reported results. Especially, a vibration mode at 1440 cm-1 shift gave a
> strong intensity.
>
> The example calculated using K points as below.
> K_POINTS AUTOMATIC
>  02 1 1 0 0 0
>
> I also tried K points increased as below.
> K_POINTS AUTOMATIC
>  10 4 4 0 0 0
> (Calculated on 54 points)
>
> However, The vibration mode of 1440 cm-1 shift is still too strong.
>
> I use Quantum Espresso (5.1.1 build on Linux). I already modify the
> source code of phq_setup.f90 in PHonon to calculate Raman using PBE-GGA
> pseudopotential.
>
> I cite input files of MASTANI-2014 examples, and teach me how to improve
> Raman intensity as same as reported simulation.
>
> Thanks in advance,
>
> Best regards,
>
> Takahiro Nakae, Ph.D
>
> Institute of Advanced Energy
> Kyoto University
>
> -gar-w_05-1H-pw.in
> &control
>    calculation       = 'scf'
>    restart_mode      = 'from_scratch'
>    prefix            = 'gar-w_05-1H'
>    tstress           = .false.
>    tprnfor           = .true.
>    wf_collect        = .true.
>    verbosity         = 'medium'
>    pseudo_dir        = '../PP_LIBRARY/'
>    outdir            = './scratch/'
>
>    etot_conv_thr     = 1e-6
>    forc_conv_thr     = 1e-5
> /
> &system
>    ibrav             = 8
>    a                 =  4.26084498661943814205
>    b                 = 13
>    c                 =  8
>
>    nat               = 18
>    ntyp              = 2
>
>    ecutwfc           = 35
> /
>    occupations       = 'smearing'
>    smearing          = 'fermi-dirac'
>    degauss           = 0.004
>
> &electrons
>    conv_thr          = 1e-9
>    mixing_beta       = 0.5
> /
> &IONS
>    trust_radius_ini  = 0.01
>    bfgs_ndim         = 3
>    pot_extrapolation = 'second_order'
>    wfc_extrapolation = 'second_order'
> /
>
> ATOMIC_SPECIES
> C 12.0107  C.pbe-mt_gipaw.UPF
> H  1.0079  H.pbe-vbc.UPF
>
> ATOMIC_POSITIONS alat
> H        0.216359182  -1.091988780  -0.000000000
> H        0.783640818  -1.091988780  -0.000000000
> C        0.339700889  -0.867654128  -0.000000000
> C        0.660299111  -0.867654128  -0.000000000
> C        0.170554615  -0.580838126  -0.000000000
> C        0.829445385  -0.580838126  -0.000000000
> C        0.330967203  -0.293018014   0.000000000
> C        0.669032797  -0.293018014  -0.000000000
> C        0.165591369   0.000000000   0.000000000
> C        0.834408631  -0.000000000   0.000000000
> C        0.330967203   0.293018014  -0.000000000
> C        0.669032797   0.293018014   0.000000000
> C        0.170554615   0.580838126   0.000000000
> C        0.829445385   0.580838126  -0.000000000
> C        0.339700889   0.867654128   0.000000000
> C        0.660299111   0.867654128   0.000000000
> H        0.216359182   1.091988780  -0.000000000
> H        0.783640818   1.091988780  -0.000000000
>
> K_POINTS AUTOMATIC
>  02 1 1 0 0 0
> -the end of file
>
> -gar-w_05-1H-ph.in
> phonons of Chevron-like ribbon at Gamma
> &inputph
>    tr2_ph            = 1e-12
>    prefix            = 'gar-w_05-1H'
>    amass(1)          =  12.0107
>    amass(2)          =   1.0079
>    outdir            = './scratch/'
>    fildyn            = 'gar-w_05-1H-ph.dyn'
>    recover           = .false.
>    epsil             = .true.
>    lraman            = .true.
>    trans             = .true.
>    fildrho           = "gar-w_05-1H-ph.fildrho"
>    max_seconds       = 350000
> /
> 0.0 0.0 0.0
> -the end of file
>
> -gar-w_05-1H-dynmat.in
> &input
>  fildyn = 'gar-w_05-1H-ph.dyn'
>  filxsf = 'gar-w_05-1H-dynmat.axsf'
>  filmol = 'gar-w_05-1H-dynmat.mold'
>  filout = 'gar-w_05-1H-dynmat.dat'
> /
> -the end of file
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum
>