Yambo Community Forum

Dear Developers,

We are using ypp to calculate the weights of some specific exciton. The output file lists the k points associate with exciton. But I am confused about the exact meaning of the number "3" and "1" which under the "Symm_kv" tag. As shown in the figure below.

Best regards,
Pang

Dear Hao Zhang,
please sign your post with your affiliation, this is a rule of the forum and you can do once for all filling the signature in your user profile.
The transition are listed in the full BZ, the k points is listed in the IBZ and then expanded with the corresponding operation symmetry of your system.
The symmetry matrix is indicated with an index, in the report file you can find the list of the symmetries together with the index.

Best,

Daniele

Dear Prof. Daniele

Thank you for your prompt reply！
The symmetry matrix is indicated with an index in the report file, whether the contents in the file correspond to the following statements?
[05.02] Symmetries
==================
DL (S)ymmetries [cc]
[S1] 1.000000 0.000000 0.000000 0.000000 1.000000 0.000000 0.000000 0.000000 1.000000
[S2]-1.000000 0.000000 0.000000 0.000000 -1.000000 0.000000 0.000000 0.000000 1.000000
[S3] 0.000000 1.000000 0.000000 1.000000 0.000000 0.000000 0.000000 0.000000 -1.000000
[S4] 0.000000 -1.000000 0.000000 -1.000000 0.000000 0.000000 0.000000 0.000000 -1.000000
[S5] 1.000000 0.000000 0.000000 0.000000 -1.000000 0.000000 0.000000 0.000000 1.000000
[S6]-1.000000 0.000000 0.000000 0.000000 1.000000 0.000000 0.000000 0.000000 1.000000
[S7] 0.000000 1.000000 0.000000 -1.000000 0.000000 0.000000 0.000000 0.000000 -1.000000
[S8] 0.000000 -1.000000 0.000000 1.000000 0.000000 0.000000 0.000000 0.000000 -1.000000
[SYMs] Time-reversal derived K-space symmetries: 9 16
[SYMs] Spatial inversion 9 is NOT a symmetry
[SYMs] Group table built correctly

Best,
Pang

Dear Pang,

yes exactly:

S1-> identity
S2-> inversion in xy plane
and so on,

they are 3x3 matrix written row by row.

Best,
Daniele