To know TO and LO modes, you have to specify the direction in k-space along which you want to see the splitting.
Also, see the post http://qe-forge.org/pipermail/pw_forum/2014-November/105682.html bests, sonu On Thu, Aug 24, 2017 at 2:58 PM, Uttam Paliwal <[email protected]> wrote: > Dear QE users > I am computing phonon frequencies for BeS. I am attaching here the output > file part > > > > q = ( 0.000000000 0.000000000 0.000000000 ) > > *********************************************************** > *************** > freq ( 1) = 0.105756 [THz] = 3.527650 [cm-1] > freq ( 2) = 0.105756 [THz] = 3.527650 [cm-1] > freq ( 3) = 0.105756 [THz] = 3.527650 [cm-1] > freq ( 4) = 16.460235 [THz] = 549.054328 [cm-1] > freq ( 5) = 16.460235 [THz] = 549.054328 [cm-1] > freq ( 6) = 16.460235 [THz] = 549.054328 [cm-1] > *********************************************************** > *************** > > Mode symmetry, T_d (-43m) point group: > > freq ( 1 - 3) = 3.5 [cm-1] --> T_2 G_15 P_4 I+R > freq ( 4 - 6) = 549.1 [cm-1] --> T_2 G_15 P_4 I+R > > > ************************************************************ > ****************** > these are TO (Transverse Optical) or LO (Longitudinal Optical), how to > know. please suggest > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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