Calculation of the Combination Scattering Spectrum of the H2O Molecule Based on the Effective Polarizability Operator

This paper presents a procedure for calculation of the combination scattering spectrum of a nonlinear molecule of the X2Y type which is based on a transformed polarizability operator taking into account the vibration-rotation interaction in the molecule to within the second order of the perturbation theory. The matrix elements of the operator are determined and classified by molecule symmetry type. The combination scattering spectrum of the H2O molecule is calculated in the region of the 2v2 band. The second derivative of the average polarizability of the H2O molecule with respect to the normal coordinate q2, associated with deformation vibrations, and the vibrational dependence of the average polarizability of the H2O molecule on the deformation quantum number v2 are estimated.