Potential energy surfaces for the ground electronic state of water, hydrogen sulfide, and hydrogen selenide

Abstract

A curvilinear internal coordinate Hamiltonian is used to calculate vibrational term values of water, hydrogen sulfide, and hydrogen selenide variationally with Morse oscillator basis functions for the stretches and harmonic oscillator basis functions for the bend. Rotational parameters, a constants, are calculated with perturbation theory expressions. Potential energy parameters are optimized with the nonlinear least-squares method using vibrational term values, a constants, and Coriolis coupling coefficients as data. The model is applied to five isotopic species of water, five isotopic species of hydrogen sulfide, and to two isotopic species of hydrogen selenide. The observed vibrational and rotational data of the studied molecules are reproduced well