[Pw_forum] Phonons calculations at Gamma
Said Asma
saidasma1987 at yahoo.fr
Tue Sep 30 18:25:25 CEST 2014
Dear QE users ans developers,
I'm a beginner in the calculation of phonons.
I did the phonons calculation of the binary AlN (rocksalt) with 16 atoms .
My output files is as following:
Diagonalizing the dynamical matrix
q = ( 0.000000000 0.000000000 0.000000000 )
**************************************************************************
freq ( 1) = 1.108833 [THz] = 36.986674 [cm-1]
freq ( 2) = 1.574620 [THz] = 52.523675 [cm-1]
freq ( 3) = 1.575398 [THz] = 52.549629 [cm-1]
freq ( 4) = 8.195754 [THz] = 273.380916 [cm-1]
freq ( 5) = 8.196815 [THz] = 273.416304 [cm-1]
freq ( 6) = 8.199734 [THz] = 273.513674 [cm-1]
freq ( 7) = 8.200351 [THz] = 273.534269 [cm-1]
freq ( 8) = 8.201724 [THz] = 273.580054 [cm-1]
freq ( 9) = 8.204042 [THz] = 273.657390 [cm-1]
freq ( 10) = 8.204069 [THz] = 273.658277 [cm-1]
freq ( 11) = 8.204305 [THz] = 273.666167 [cm-1]
freq ( 12) = 9.560810 [THz] = 318.914296 [cm-1]
freq ( 13) = 9.561375 [THz] = 318.933138 [cm-1]
freq ( 14) = 9.564736 [THz] = 319.045240 [cm-1]
freq ( 15) = 9.565551 [THz] = 319.072451 [cm-1]
freq ( 16) = 9.568429 [THz] = 319.168422 [cm-1]
freq ( 17) = 9.569095 [THz] = 319.190663 [cm-1]
freq ( 18) = 12.351077 [THz] = 411.987578 [cm-1]
freq ( 19) = 12.431223 [THz] = 414.660977 [cm-1]
freq ( 20) = 12.439828 [THz] = 414.947983 [cm-1]
freq ( 21) = 12.782122 [THz] = 426.365702 [cm-1]
freq ( 22) = 12.796523 [THz] = 426.846069 [cm-1]
freq ( 23) = 12.854425 [THz] = 428.777481 [cm-1]
freq ( 24) = 12.908753 [THz] = 430.589665 [cm-1]
freq ( 25) = 12.916648 [THz] = 430.852986 [cm-1]
freq ( 26) = 12.923203 [THz] = 431.071665 [cm-1]
freq ( 27) = 12.940057 [THz] = 431.633836 [cm-1]
freq ( 28) = 12.951841 [THz] = 432.026913 [cm-1]
freq ( 29) = 13.043933 [THz] = 435.098776 [cm-1]
freq ( 30) = 13.090098 [THz] = 436.638683 [cm-1]
freq ( 31) = 13.091268 [THz] = 436.677691 [cm-1]
freq ( 32) = 16.509761 [THz] = 550.706361 [cm-1]
freq ( 33) = 16.566717 [THz] = 552.606181 [cm-1]
freq ( 34) = 16.587373 [THz] = 553.295203 [cm-1]
freq ( 35) = 16.640103 [THz] = 555.054089 [cm-1]
freq ( 36) = 16.658006 [THz] = 555.651280 [cm-1]
freq ( 37) = 16.692001 [THz] = 556.785223 [cm-1]
freq ( 38) = 19.936035 [THz] = 664.994532 [cm-1]
freq ( 39) = 19.939099 [THz] = 665.096767 [cm-1]
freq ( 40) = 19.940916 [THz] = 665.157356 [cm-1]
freq ( 41) = 19.955181 [THz] = 665.633197 [cm-1]
freq ( 42) = 21.966886 [THz] = 732.736442 [cm-1]
freq ( 43) = 21.984557 [THz] = 733.325899 [cm-1]
freq ( 44) = 22.013871 [THz] = 734.303712 [cm-1]
freq ( 45) = 22.697394 [THz] = 757.103583 [cm-1]
freq ( 46) = 22.729742 [THz] = 758.182599 [cm-1]
freq ( 47) = 22.771292 [THz] = 759.568539 [cm-1]
freq ( 48) = 22.788849 [THz] = 760.154171 [cm-1]
***********************************************************************
It has 16 atoms then we have 48 frequencies, 3 acoustic (which tend to 0) and 46 optical frenquencies, but how can I differentiate between longitudinal and transverse waves frequency?
I looked at the file occurs, I found the displacements of atoms, but I was not able to distinguish between transeverse and longitudinal optical modes.
Below is an example of the frequencies in the dynamical matrix file :
freq ( 4) = 8.195754 [THz] = 273.380916 [cm-1]
( 0.000000 0.000000 -0.044678 0.000000 0.044678 0.000000 )
( 0.000000 0.000000 0.002637 0.000000 -0.002637 0.000000 )
( -0.164130 0.000000 0.393942 0.000000 -0.051695 0.000000 )
( 0.005529 0.000000 0.003753 0.000000 0.001833 0.000000 )
( 0.000000 0.000000 0.229388 0.000000 -0.229388 0.000000 )
( 0.000000 0.000000 0.001731 0.000000 -0.001731 0.000000 )
( -0.167162 0.000000 -0.054230 0.000000 0.438521 0.000000 )
( 0.003854 0.000000 -0.000832 0.000000 -0.004534 0.000000 )
( 0.164130 0.000000 0.051695 0.000000 -0.393942 0.000000 )
( -0.005529 0.000000 -0.001833 0.000000 -0.003753 0.000000 )
( 0.000000 0.000000 -0.188464 0.000000 0.188464 0.000000 )
( 0.000000 0.000000 0.006472 0.000000 -0.006472 0.000000 )
( 0.167162 0.000000 -0.438521 0.000000 0.054230 0.000000 )
( -0.003854 0.000000 0.004534 0.000000 0.000832 0.000000 )
( 0.000000 0.000000 0.041543 0.000000 -0.041543 0.000000 )
( 0.000000 0.000000 0.004383 0.000000 -0.004383 0.000000 )
freq ( 5) = 8.196815 [THz] = 273.416304 [cm-1]
( 0.553586 0.000000 -0.066816 0.000000 -0.066816 0.000000 )
( -0.022611 0.000000 -0.004384 0.000000 -0.004384 0.000000 )
( -0.050218 0.000000 -0.248855 0.000000 -0.082446 0.000000 )
( -0.000781 0.000000 0.002840 0.000000 0.001799 0.000000 )
( -0.187313 0.000000 -0.127347 0.000000 -0.127347 0.000000 )
( 0.002035 0.000000 -0.000907 0.000000 -0.000907 0.000000 )
( 0.049241 0.000000 0.085657 0.000000 0.277200 0.000000 )
( -0.004321 0.000000 -0.001756 0.000000 -0.007275 0.000000 )
( -0.050218 0.000000 -0.082446 0.000000 -0.248855 0.000000 )
( -0.000781 0.000000 0.001799 0.000000 0.002840 0.000000 )
( 0.148869 0.000000 0.104419 0.000000 0.104419 0.000000 )
( -0.007221 0.000000 -0.002029 0.000000 -0.002029 0.000000 )
( 0.049241 0.000000 0.277200 0.000000 0.085657 0.000000 )
( -0.004321 0.000000 -0.007275 0.000000 -0.001756 0.000000 )
( -0.498090 0.000000 0.065208 0.000000 0.065208 0.000000 )
( 0.005159 0.000000 -0.002368 0.000000 -0.002368 0.000000 )
freq ( 6) = 8.199734 [THz] = 273.513674 [cm-1]
( 0.000000 0.000000 -0.016697 0.000000 0.016697 0.000000 )
( 0.000000 0.000000 -0.011124 0.000000 0.011124 0.000000 )
( -0.282827 0.000000 -0.268330 0.000000 -0.074618 0.000000 )
( 0.007226 0.000000 -0.003886 0.000000 0.008910 0.000000 )
( 0.000000 0.000000 0.305360 0.000000 -0.305360 0.000000 )
( 0.000000 0.000000 -0.007286 0.000000 0.007286 0.000000 )
( -0.279901 0.000000 -0.077837 0.000000 -0.279063 0.000000 )
( 0.009124 0.000000 -0.007508 0.000000 0.003791 0.000000 )
( 0.282827 0.000000 0.074618 0.000000 0.268330 0.000000 )
( -0.007226 0.000000 -0.008910 0.000000 0.003886 0.000000 )
( 0.000000 0.000000 -0.292826 0.000000 0.292826 0.000000 )
( 0.000000 0.000000 -0.001182 0.000000 0.001182 0.000000 )
( 0.279901 0.000000 0.279063 0.000000 0.077837 0.000000 )
( -0.009124 0.000000 -0.003791 0.000000 0.007508 0.000000 )
( 0.000000 0.000000 0.019674 0.000000 -0.019674 0.000000 )
( 0.000000 0.000000 -0.004853 0.000000 0.004853 0.000000 )
with respectful regards
***********************************************
Said Asma,
PhD. LMCN,
Faculté des sciences de Monastir,
Avenue de l'environnement 5019-Monastir,Tunisie
E-mail :saidasma1987 at yahoo.fr
***********************************************
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