[Pw_forum] negative values in XANES

[jiayudai]

Dear developers and users,

I am doing the calculation for the XANES of CHx system. There is a problem that the absorption is always negative, locating at about -100 eV. According to my understanding, the absorption should be positive. Besides, the fermi energy in my systems is very high, about tens of eV (high pressure). Therefore, if i used the cutoff of fermi energy, the absorption should be very small. Is it reasonable? Or there is some problems in the calculations?

Thanks in advance.

Jiayu
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Jiayu Dai
Department of Physics
National University of Defense Technology, 
Changsha, 410073, P R China
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