Use of trigonometric series for solution of the Schrödinger equation for bending vibrations in triatomic molecules

Abstract
A method is proposed suitable for an ab initio treatment of bending vibrations in triatomic molecules. The potentials and kinetic energy terms are represented by Fourier series and the hamiltonian is diagonalized in a basis of trigonometric functions. The calculation of the bending energy levels and corresponding wavefunctions for nondegenerate and degenerate electronic states, as well as of transition probabilities between various vibronic species is described. The approach is tested on the C3 and NH2 molecules.