I met a problem of XAS calculation with BSE, maybe it's a bug of Excting code.
I calculated the XAS of a H2 crystal strcture, from the Ground state calculation some of the valence bands have positive energy.
So the energy edge to excite these band is negative.
Then in the calcualted result, we obtain negative intensity in the negative energy
range, which is obviouly incorrect.
Is there anyone have ever met this problem?
Appreciate for any help!