On the parametric theory and method for calculating Raman scattering intensities of polyatomic molecules

It is shown that the Heisenberg-Kramers formula for the Raman tensor components can be approximated well by the sum of two terms: the derivative of classical polarizability with respect to the normal coordinate, plus the rapidly convergent series. A method for evaluating the individual terms of this sum is suggested that allows one to ignore the infinite series. The limiting case of the parametric semiempirical Raman scattering theory is shown to amount either to the conventional valence-optical scheme (VOS) supplemented by an additional term in the form of a rapidly convergent series, or simply to a modified VOS. 12 refs