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 / [email protected] / 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
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