Where can I find excitation energies?

[chinaye]

Dear developers,
I performed the BSE calculation by diagonalizing the BS matrix. Where can I find the excitation energies? Should I use some special keywords in the input file to write the excitation energies in the output file explicitly? Thank you very much.

[myrta gruning]

Dear Jianfei Ye

to get information on the excitation energies you should use the ypp (yambo post processing tool, ypp -H for invoking the help)

>ypp -e s

will produce the lists of excitations sorted by the intensity (I) and by the energies (E):
o.exc_E_sorted
o.exc_I_sorted

if you wish you can further analyse the excitation spectrum in terms of eh pairs with

>ypp -e a
for the desired excitation (the numbering as in o.exc_E_sorted) you can obtain (here e.g. for the 5th excitation in the list)
o.exc_amplitude_at_5
o.exc_weights_at_5

where the amplitude for the eigenstate g of the BS Hamiltonian is
A_g(\omega)= \sum_{eh} |<eh|g>|^2 \delta(\omega - E_{eh})

|<eh|g>|^2 is the weight of the eh pair
E_{eh} is energy of the eh pair
the weights and corresponding eh energies are listed in the file o.exc_weights_at_5
from o.exc_amplitude_at_5 you can plot A_g

you can also plot the excitonic wave function

>ypp -e w
>ypp -e w -f

but in this case the diagonalization has to be performed with the (uncommented) key

WRbsWF # [BSS] Write to disk excitonic the FWs

Have fun!

Regards,
m

[chinaye]

Dear Dr Myrta Grüning,
thank you for your reply. Your information are very helpful.