Broadening effect in optical spectrum

[jihang]

I am computing frequency dependent dielectric functions by following the example from vaspwiki.
(http://cms.mpi.univie.ac.at/wiki/index. ... c_response)


It works well, and I got imaginary dielectric function as a function of energy. However, broadening effect looks too big. The values between zero and band gap are quite large so it is difficult to determine optical band gap from the spectrum.

Could anyone tell me which tag is related with the broadening effect in optical spectrum (or imaginary dielectric function)?

I tried different CSHIFT, NEDOS, SIGMA, and NOMEGA to decrease broadening effect for sharp peak, but all of them did not work. I'd really appreciate it if you could help me to find proper tag or parameter in VASP!
<span class='smallblacktext'>[ Edited ]</span>

[support_vasp]

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