How to obtain the irreducible representations of the electronic bands ?

DLP

Hi,

I would like to obtain the irreducible representations of the eigenstates for a given crystal at each k-point. To do so, I am running properties with the following .d3 file:

NEWK
0 0
0 2
66 1
67 1
END

The output file (.outp) gives me the eigenvalues at each k-point with a label, for instance A'',A',E'',etc. In that same .outp file there is a list of character tables, which I assume that each character table corresponds to a k-point in order of appearance. However, the irreps that appear in the n-th character table do not correspond to the irreps that appear in the n-th set of eigenvalues, meaning that you can have an irrep labelled B3 in the eigenvalues but for the corresponding character table there is no B3 irrep. How can I identify what the irreps of the eigenstates actually are or how they transform under the symmetry operations of the little point group ?

GiacomoAmbrogio

Hi DLP,

NEWK
0 n

is used to specify an anisotropic shrinking factor. However in you input you are not providing the three parameters required for this, which makes the usage unclear.

Could you please attach the output file you are referring to, so that I can take a closer look?

DLP

Hi GiacomoAmbrogio ,

I have attached the properties output file below so you can take a look. If there is anything else you want to check let me know.

hBN.outp

The main issue that I have is that, for instance, the set of eigenvalues at K= 91 ( 10 10 0) (which starts at line 2396 of the file) has labels that corresponds to the irrep of each band at that k point. You will find that in that same file, there is a list of character tables. However, the labels of the irreps that appear in the last character table is not the same as the labels that appear in the last set of eigenvalues. In general it seems that the n-th character table that appears does not contain the same irreps as the n-th set of eigenvalues. In other words, I do not know to what k-point each character table is referring to in order to properly identify the irreps.