[Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF

Lorenzo Paulatto lorenzo.paulatto at impmc.upmc.fr
Fri Nov 21 11:00:40 CET 2014


You can define a band as being LO or TO by continuity, but it won't 
necessarily be Longitudinal or Transverse i nthe entire Brillouin zone. 
In particular, from the [1/2 1/2 1/2] point I cannot say anything. 
Especially since I do not know our cell geometry.

kind regards


On 20/11/14 17:43, Kondaiah Samudrala wrote:
> Dear Sir,
> Sorry for the eps figure. Now I attached new figure with pdf
> extension.... In the mean time, I am following the same definition for
> LO-TO splitting at Gamma point level.  But, I am not clear about the
> below sentence far from Gamma.
>
>
> "An the end of the dynamical matrix file you have the frequencies and
> the atom displacements (3 times number of atoms complex numbers). If the
> displacement for every atom is parallel to the q-point, the mode is
> Longitudinal; if it is orthogonal, the mode is Transverse. In every
> other case it is neither. You can then associated the frequency with the
> label.".
>
> I would like to know that is there any possibility to know more details
> far from Gamma point. Here with I am adding the ip and ops of matdyn.x (
> Here I am using only one special point in the IBZ)
>
> *Matdyn.in :*
> &input
>     asr='crystal',q_in_band_form=.true.
>      fleig='matdyn.eig', fldyn='AB22.dyn',flfrc='AB2444_with_ASR.fc',
> flfrq='AB2_with_ASR.freq'
>   /
>   1
>   0.5 0.5 0.5 2
>
> *AB2.dyn* :
>   Dynamical  Matrix in cartesian axes
>
>       q = (    0.500000000   0.500000000   0.500000000 )
>
>      1    1
>    0.03952920  0.00000000   -0.00374183  0.00000000    0.00000000
>   0.00000000
>   -0.00374183  0.00000000    0.03952920  0.00000000    0.00000000
>   0.00000000
>    0.00000000  0.00000000    0.00000000  0.00000000    0.29542189
>   0.00000000
>      1    2
>    0.02007831 -0.00022229   -0.01131717  0.00672504    0.00000000
>   0.00000000
>   -0.01131717  0.00672504    0.02007831 -0.00022229    0.00000000
>   0.00000000
>    0.00000000  0.00000000    0.00000000  0.00000000   -0.03673002
>   0.00282937
>      1    3
>   -0.04191744  0.00000006    0.00162178 -0.00069950    0.00000000
>   0.00000000
>    0.00162178 -0.00069950   -0.04191744  0.00000006    0.00000000
>   0.00000000
>    0.00000000  0.00000000    0.00000000  0.00000000   -0.25545367
> -0.00387305
>      2    1
>    0.02007831  0.00022229   -0.01131717 -0.00672504    0.00000000
>   0.00000000
>   -0.01131717 -0.00672504    0.02007831  0.00022229    0.00000000
>   0.00000000
>    0.00000000  0.00000000    0.00000000  0.00000000   -0.03673002
> -0.00282937
>      2    2
>    0.03952920  0.00000000   -0.00374183  0.00000000    0.00000000
>   0.00000000
>   -0.00374183  0.00000000    0.03952920  0.00000000    0.00000000
>   0.00000000
>    0.00000000  0.00000000    0.00000000  0.00000000    0.29542189
>   0.00000000
>      2    3
>   -0.04191744 -0.00000006    0.00162178  0.00069950    0.00000000
>   0.00000000
>    0.00162178  0.00069950   -0.04191744 -0.00000006    0.00000000
>   0.00000000
>    0.00000000  0.00000000    0.00000000  0.00000000   -0.25545367
>   0.00387305
>      3    1
>   -0.04191744 -0.00000006    0.00162178  0.00069950    0.00000000
>   0.00000000
>    0.00162178  0.00069950   -0.04191744 -0.00000006    0.00000000
>   0.00000000
>    0.00000000  0.00000000    0.00000000  0.00000000   -0.25545367
>   0.00387305
>      3    2
>   -0.04191744  0.00000006    0.00162178 -0.00069950    0.00000000
>   0.00000000
>    0.00162178 -0.00069950   -0.04191744  0.00000006    0.00000000
>   0.00000000
>    0.00000000  0.00000000    0.00000000  0.00000000   -0.25545367
> -0.00387305
>      3    3
>    0.10704556  0.00000000   -0.00739632  0.00000000    0.00000000
>   0.00000000
>   -0.00739632  0.00000000    0.10704556  0.00000000    0.00000000
>   0.00000000
>    0.00000000  0.00000000    0.00000000  0.00000000    0.54383493
>   0.00000000
>
> *matdyn.modes:*
>
>      diagonalizing the dynamical matrix ...
>
>   q =       0.5000      0.5000      0.5000
>   **************************************************************************
>       freq (    1) =       1.318544 [THz] =      43.981900 [cm-1]
>   ( -0.411001   0.032309    -0.411001   0.032309     0.000000   0.000000   )
>   ( -0.381067  -0.157332    -0.381067  -0.157332     0.000000   0.000000   )
>   ( -0.395193  -0.062378    -0.395193  -0.062378     0.000000   0.000000   )
>       freq (    2) =       1.662161 [THz] =      55.443739 [cm-1]
>   (  0.000000   0.000000     0.000000   0.000000     0.578232   0.001810   )
>   (  0.000000   0.000000     0.000000   0.000000     0.578232  -0.001810   )
>   (  0.000000   0.000000     0.000000   0.000000     0.575577   0.000000   )
>       freq (    3) =       2.140009 [THz] =      71.383008 [cm-1]
>   (  0.249628   0.355541    -0.249628  -0.355541     0.000000   0.000000   )
>   (  0.274220  -0.336937    -0.274220   0.336937     0.000000   0.000000   )
>   (  0.349855   0.012425    -0.349855  -0.012425     0.000000   0.000000   )
>       freq (    4) =       2.763777 [THz] =      92.189664 [cm-1]
>   ( -0.043052   0.489305     0.043052  -0.489305     0.000000   0.000000   )
>   ( -0.032204  -0.490138     0.032204   0.490138     0.000000   0.000000   )
>   ( -0.132110  -0.001463     0.132110   0.001463     0.000000   0.000000   )
>       freq (    5) =       4.043036 [THz] =     134.861157 [cm-1]
>   ( -0.061283   0.494864    -0.061283   0.494864     0.000000   0.000000   )
>   ( -0.060611  -0.494947    -0.060611  -0.494947     0.000000   0.000000   )
>   (  0.052041   0.000035     0.052041   0.000035     0.000000   0.000000   )
>       freq (    6) =       5.972075 [THz] =     199.206984 [cm-1]
>   ( -0.480641  -0.101587    -0.480641  -0.101587     0.000000   0.000000   )
>   ( -0.478284   0.112159    -0.478284   0.112159     0.000000   0.000000   )
>   (  0.131633  -0.001451     0.131633  -0.001451     0.000000   0.000000   )
>       freq (    7) =       7.226719 [THz] =     241.057396 [cm-1]
>   ( -0.493843   0.042446     0.493843  -0.042446     0.000000   0.000000   )
>   ( -0.492606  -0.054977     0.492606   0.054977     0.000000   0.000000   )
>   (  0.092914   0.001180    -0.092914  -0.001180     0.000000   0.000000   )
>       freq (    8) =      14.341371 [THz] =     478.376650 [cm-1]
>   (  0.000000   0.000000     0.000000   0.000000    -0.432733   0.552169   )
>   (  0.000000   0.000000     0.000000   0.000000    -0.432733  -0.552169   )
>   (  0.000000   0.000000     0.000000   0.000000     0.125310   0.000000   )
>       freq (    9) =      14.493257 [THz] =     483.443015 [cm-1]
>   (  0.000000   0.000000     0.000000   0.000000    -0.491770  -0.497872   )
>   (  0.000000   0.000000     0.000000   0.000000    -0.491770   0.497872   )
>   (  0.000000   0.000000     0.000000   0.000000     0.143430   0.000000   )
>   **************************************************************************
>
> *AB2.freq*
>
>   &plot nbnd=   9, nks=   1 /
>              0.500000  0.500000  0.500000
>     43.9819   55.4437   71.3830   92.1897  134.8612  199.2070
>    241.0574  478.3766  483.4430
>
> with regards
> S. Appalakondaiah
> PhD Schloar
> University of Hyderabad
>
>
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>

-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05



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