[Pw_forum] Raman calculation of graphyne

Barnali Bhattacharya barnalidgbhatt at gmail.com
Thu Jun 23 05:34:08 CEST 2016


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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