[Wien] optic sum rules

[ali ghafari]

Dear Prof. Blaha

I have calculated the optical properties of TiSe2 by MBJ potential with 6000, 50000 and 90000 kpoints which generated after scf by x kgen as discussed in the UG.
As discussed in the paper of Prof. Claudia Draxl (computer physics comm. 175, 1-14 (2006)) the sum rule 1 and 2 show 'an effective number of electrons contributing to the absoption process as a function of energy'.
but my calculations lead to :
6000 kpoints:   

sum rule 1: Int(sigma)dw      19.14 
sum rule 2: Int(eloss.w)dw    18.93
sum rule 3: Int(eloss/w)dw    1.51
50000 kpoints

sum rule 1: Int(sigma)dw      19.08
sum rule 2: Int(eloss.w)dw    18.94
sum rule 3: Int(eloss/w)dw    1.52

90000 kpoints

sum rule 1: Int(sigma)dw      10.125 
sum rule 2: Int(eloss.w)dw    10.035
sum rule 3: Int(eloss/w)dw    1.51
the results show that in 90000 kpoints the value of 'sum rule 2' significantly decreases . in the UG it has mensioned that for the optic we need dense kpoints but how many? how can I check it for optic? 
Best Regards 

Ali
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