Hi,
I was wondering if VASP supports spectrum calculations and if so what TAGS should be added into the INCAR? I did some research and it looks like it is LOPTICS? Is that correct?
Many thanks,
Jess
Dear Jess,
What system are you studying and what kind of interactions do you want to consider? This greatly influences the type of calculation you should perform.
Kind regards,
Pedro
Hi Pedro,
It is looking at different minerals and looking at their IR spec. However what other spec properties can Vasp look at?
Many thanks,
Jess
Also reflectivity 
Dear Jess,
Both infrared absorption and reflectivity can be computed from the dynamical dielectric function, \(\epsilon(\omega)\). In the page Category:Dielectric properties you can find details on all possible calculations that VASP can perform for \(\epsilon(\omega)\), the approximations involved, and links to the respective pages.
I suggest that you start by exploring our wiki and tutorials and try to understand which calculation type is most appropriate for what you want to study. From there the specific INCAR tags should become evident.
Kind regards,
Pedro