On Mon, 2017-05-29 at 19:31 +0800, balabi wrote: > Thank you so much for reply. > > > I thought nosym is just used for preventing additional k points to be > generated. The documentation doesn't say that nosym will make > symmetry analysis fail. > > > Besides, I rerun the calculation, turning off nosym. But There comes > another problem. > > > A partial output of bands.x now for gamma point is below > > > Band symmetry, D_3d (-3m) double point group: > > > e( 1 - 4) = -16.63750 eV 4 --> G_5+ L_4+ > e( 1 - 4) = -16.63750 eV 4 --> G_6+ L_5+ > e( 1 - 4) = -16.63750 eV 4 --> G_5- L_4- > e( 1 - 4) = -16.63750 eV 4 --> G_6- L_5- > e( 5 - 6) = -16.62527 eV 2 --> G_4+ L_6+ > e( 7 - 8) = -16.62265 eV 2 --> G_4- L_6- > e( 9 - 10) = -13.66107 eV 2 --> G_4- L_6- > e( 11 - 12) = -13.65905 eV 2 --> G_4+ L_6+ > e( 13 - 14) = -13.64175 eV 2 --> G_4+ L_6+ > e( 15 - 16) = -13.63940 eV 2 --> G_5+ L_4+ > > The number is the degeneracy of the band. In this case there are four degenerate bands and their symmetry is G_5+ + G_6+ + G_5- + G_6-. Sometimes the bands are more degenerate than predicted by group theory due to time reversal (the additional degeneracy due to time reversal is not analyzed by the routine). In other cases there might also be some accidental degeneracy. In any case the reducible representation is correctly decomposed in terms of its irreducible representations.
HTH, Andrea > Previously I thought the number right before the arrow means > duplication of the same symmetry. But the above output make this > assumption false. What does number 4 mean in " e( 1 - 4) = > -16.63750 eV 4 --> G_5+ L_4+"?? > And since the e(1-4) four bands each has different symmetry, why don't > they write like this > > > e( 1 - 1) = -16.63750 eV 1 --> G_5+ L_4+ > e( 2 - 2) = -16.63750 eV 1 --> G_6+ L_5+ > e( 3 - 3) = -16.63750 eV 1 --> G_5- L_4- > e( 4 - 4) = -16.63750 eV 1 --> G_6- L_5- > > > Thank you for helping > > > > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum -- Andrea Dal Corso Tel. 0039-040-3787428 SISSA, Via Bonomea 265 Fax. 0039-040-3787249 I-34136 Trieste (Italy) e-mail: [email protected] _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
