# [Pw_forum] The symmetry of bands

Fri Apr 3 14:22:48 CEST 2009

```Thank you for your help concerning plotband.x and bands.x.

2009/4/3 Gabriele Sclauzero <sclauzer at sissa.it>

>
>
>
> > My questions are:
> > 1. Why the calculated top of valence bands (15th, and 16th ) do not
> > split as reported work (Appl. Phys. Lett.83,5163)?
> > 2. In the spin.dat.rap file, what does the symbol "T" stand for?  And
> > what does the "1       2       5       6       5       6       5  ..."
> mean?
>
> I can reply to the second, for the moment:
> T is a flag, needed by plotband.x program, which identifies k-point which
> have a different
> symmetry with respect to the preceeding. It is meant to identify the
> special k-point in
> your k-point path used for plotting the bands. Since you have only one
> k-point in this
>
> The numbers on the rows are the representations to which the corresponding
> eigenvalues
> (those listed in the filband file) belong. The representations are listed
> in the standard
> output of bands.x, so that to each number you can associate an irreducible
> representation.
>
> GS
>
>  > The calculated results of the band structure at Gamma point is as
> following:
>  > spin.dat:
>  >  &plot nbnd=  30, nks=   1 /
>  >             0.000000  0.000000  0.000000
>  >   -8.070  -8.070  -5.968  -5.968   1.092   1.092   6.154   6.154
>  > 6.169   6.169
>  >    6.803   6.803   6.816   6.816   7.015   7.015  11.136  11.136
>  > 13.603  13.603
>  >   17.513  17.513  18.094  18.094  18.118  18.118  19.967  19.967
>  > 20.042  20.042
>  >
>  > spin.dat.rap:
>  >  &plot_rap nbnd_rap=  30, nks_rap=   1 /
>  >             0.000000  0.000000  0.000000    T
>  >        1       2       5       6       5       6       5       6
>  > 3       4
>  >        1       2       3       4       1       2       1       2
>  > 5       6
>  >        5       6       1       2       3       4       1       2
>  > 5       6
>
>
>
> --
>
>
> o ------------------------------------------------ o
> | Gabriele Sclauzero, PhD Student                  |
> | c/o:   SISSA & CNR-INFM Democritos,              |
> |        via Beirut 2-4, 34014 Trieste (Italy)     |
> | email: sclauzer at sissa.it                         |
> | phone: +39 040 3787 511                          |
> | skype: gurlonotturno                             |
> o ------------------------------------------------ o
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--
Y. C. Cheng
Department of Phyics
Nanjing University
Nanjing 210093
P. R. China
Tel: 86-25-83592907
Email: yccheng.nju at gmail.com
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