Dear Barnali,
The symmetries stem from the self-consistent calculation, so the problem
is there. Indeed it looks from the few coordinates in the input that you
provided that they are not precisely - up to some 4-5 digits on the
symmetric positions like 0.5; thus 'pw.x' does not consider these as
symmetries and all the modes become labelled with the basic symmetry "A".
Please try symmetrising the coordinates, checking already in the output of
'pw.x' that you have the symmetry requested.
Greetings from Paris,
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 Thu, 23 Jun 2016, Barnali Bhattacharya wrote:
Dear Sir/Madam
I am trying to reproduce the Raman spectra of graphyne system reported by Zhang et al [J. Phys. Chem. C, 2016, 120 (19), pp 10605–10613].
In my calculated spectra, I have found the Raman peaks are located more or less on same frequency as observed in the paper of Zhang et al. The position of the Raman peaks are given below-
…………………
# mode [cm-1] [THz] IR Raman depol.fact
1 -0.00 -0.0000 0.0000 0.0000 0.7265
2 -0.00 -0.0000 0.0000 0.0000 0.7498
3 0.00 0.0000 0.0000 0.0001 0.5641
4 180.32 5.4057 0.0000 1.4898 0.2967
5 180.47 5.4103 0.0000 1.5604 0.7466
6 232.43 6.9680 0.0000 51.4183 0.7500
7 232.84 6.9804 0.0000 59.4666 0.7500
8 249.23 7.4716 0.0000 955497.8547 0.1945
9 333.27 9.9912 0.0276 6.5036 0.6017
10 401.52 12.0373 0.0000 0.0027 0.3409
11 413.75 12.4038 0.0589 0.0026 0.5983
12 414.29 12.4201 0.0586 0.0128 0.2304
13 465.96 13.9692 0.0003 0.0051 0.7477
14 506.14 15.1738 0.0000 4286930.6335 0.1763
15 506.61 15.1879 0.0000 153395.9276 0.3020
16 557.47 16.7124 0.0001 3677.4093 0.7500
17 557.63 16.7175 0.0001 4445.0962 0.7500
18 672.04 20.1471 0.0000 0.0257 0.6204
19 679.01 20.3562 0.0000 5.2659 0.6276
20 679.11 20.3593 0.0000 10.5107 0.2863
21 788.70 23.6446 0.0000 14647549.8132 0.1986
22 793.96 23.8025 0.0000 0.0232 0.7498
23 948.26 28.4280 0.0000 3919030.7925 0.2311
24 948.36 28.4312 0.0000 1167947.1815 0.2501
25 1059.37 31.7591 3.1810 4.7302 0.2109
26 1059.64 31.7672 3.1760 0.1304 0.2298
27 1205.12 36.1285 0.0000 56577350.6847 0.2012
28 1388.64 41.6303 0.0000 0.0043 0.6020
29 1465.22 43.9261 0.0000 710764.1488 0.6076
30 1465.26 43.9274 0.0000 1596968.3457 0.3793
31 1482.91 44.4565 0.0018 4.9641 0.3255
32 1501.10 45.0019 23.8090 1.7968 0.3140
33 1501.37 45.0098 23.7976 0.3151 0.3348
34 2191.33 65.6945 0.0000 162172387.6538 0.1964
35 2230.26 66.8616 0.0000 3616106.5565 0.1860
36 2231.11 66.8870 0.0000 2730839.0109 0.1988
……………………………………………………………………….
But the problem arises in the case of mode symmetry and irreducible representation calculation.
I am not able to generate same irreducible representation like Zhang has got.
Of course, I have missed some technique or something wrong with my understanding.
My calculated irreducible representations are presented below-
……………………..
Mode symmetry, C_1 (1) point group:
freq ( 1 - 1) = 0.6 [cm-1] --> A I+R
freq ( 2 - 2) = 3.2 [cm-1] --> A I+R
freq ( 3 - 3) = 17.3 [cm-1] --> A I+R
freq ( 4 - 4) = 180.3 [cm-1] --> A I+R
freq ( 5 - 5) = 180.5 [cm-1] --> A I+R
freq ( 6 - 6) = 232.4 [cm-1] --> A I+R
freq ( 7 - 7) = 232.8 [cm-1] --> A I+R
freq ( 8 - 8) = 249.2 [cm-1] --> A I+R
freq ( 9 - 9) = 333.3 [cm-1] --> A I+R
freq ( 10 - 10) = 401.5 [cm-1] --> A I+R
freq ( 11 - 11) = 413.7 [cm-1] --> A I+R
freq ( 12 - 12) = 414.3 [cm-1] --> A I+R
freq ( 13 - 13) = 466.0 [cm-1] --> A I+R
freq ( 14 - 14) = 506.1 [cm-1] --> A I+R
freq ( 15 - 15) = 506.6 [cm-1] --> A I+R
freq ( 16 - 16) = 557.5 [cm-1] --> A I+R
freq ( 17 - 17) = 557.6 [cm-1] --> A I+R
freq ( 18 - 18) = 672.0 [cm-1] --> A I+R
freq ( 19 - 19) = 679.0 [cm-1] --> A I+R
freq ( 20 - 20) = 679.1 [cm-1] --> A I+R
freq ( 21 - 21) = 788.7 [cm-1] --> A I+R
freq ( 22 - 22) = 794.0 [cm-1] --> A I+R
freq ( 23 - 23) = 948.3 [cm-1] --> A I+R
freq ( 24 - 24) = 948.4 [cm-1] --> A I+R
freq ( 25 - 25) = 1059.4 [cm-1] --> A I+R
freq ( 26 - 26) = 1059.6 [cm-1] --> A I+R
freq ( 27 - 27) = 1205.1 [cm-1] --> A I+R
freq ( 28 - 28) = 1388.6 [cm-1] --> A I+R
freq ( 29 - 29) = 1465.2 [cm-1] --> A I+R
freq ( 30 - 30) = 1465.3 [cm-1] --> A I+R
freq ( 31 - 31) = 1482.9 [cm-1] --> A I+R
freq ( 32 - 32) = 1501.1 [cm-1] --> A I+R
freq ( 33 - 33) = 1501.4 [cm-1] --> A I+R
freq ( 34 - 34) = 2191.3 [cm-1] --> A I+R
freq ( 35 - 35) = 2230.3 [cm-1] --> A I+R
freq ( 36 - 36) = 2231.1 [cm-1] --> A I+R
……………………………………..
My questions are
1. How can I generate the correct irreducible representation for graphyne?
Please suggest me the correct path.
Here I have attached the input files (grapyne.scf.in and graphyne.phonon.in)
for details information.
2. I have calculated the Raman spectra of graphene with the same procedure
and found exact irreducible representation. Why problem arises in the case of
graphyne? Because graphene and
graphyne have same hexagonal symmetry.
I am waiting for any reply. Any help will be thankfully acknowledged.
Thanking you.
Sincerely
Barnali Bhattacharya
Ph.D student
Department of physics
Assam University
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