Time-dependent density functional theory applied to Raman scattering from methane

The geometric derivatives of the polarizability are related to non-resonance Raman spectra. Although a common approximation is to proceed with the derivatives of the static polarizability, it is important to account for the frequency of the incident photon when calculating such properties as differential Raman cross-sections. We apply the time-dependent coupled current Kohn-Sham theory of Colwell et al. to the Raman scattering from methane. Our results show that it is not untypical for the geometric derivatives of the polarizability to change by ten percent when we move from the static approximation to frequencies that correspond to common exciting lasers.