[Pw_forum] Reproduce Raman simulation of Graphene nanoribbon using QE

[Takahiro Nakae]

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