[Pw_forum] question about k-mesh density and difference between calculated and experimental infrared

[Shaofeng Wang]

Dear all,

I am calculating the infrared spectra of gypsum supercell (2*1*2) with the 
dimension of 13*15*11 A at gamma point. My question is if gamma point is 
enough to calculate the accurate infrared spectra. In addition, why are the 
frequencies of calculated spectra always lower than those of experimental 
spectra?

Any help is very appriciated.

Regards,

Shaofeng



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Shaofeng Wang, Ph.D of Geochemistry
Environmental Molecular Science Group
Institute of Applied Ecology, Chinese Academy of Sciences
Shenyang, 110016, China
wangshaofeng at iae.ac.cn
www.iae.cas.cn