[Pw_forum] Raman calculation of graphyne

Ari P Seitsonen Ari.P.Seitsonen at iki.fi
Thu Jun 23 07:08:48 CEST 2016


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 / 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 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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