TIME-DEPENDENT DENSITY-FUNCTIONAL THEORY APPLIED TO RAMAN-SCATTERING FROM METHANE

The geometric derivatives of the polarizability are related to non-res onance Raman spectra. Although a common approximation is to proceed wi th the derivatives of the static polarizability, it is important to ac count for the frequency of the incident photon when calculating such p roperties as differential Raman cross-sections. We apply the time-depe ndent 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 perc ent when we move from the static approximation to frequencies that cor respond to common exciting lasers. (C) 1997 Elsevier Science B.V.