Improvement of the effective nuclear charge model for triatomic molecules—VII

Abstract

The effective nuclear charge model previously proposed for predicting the quadratic valence force constants of polyatomic molecules is further developed to allow the prediction of their anharmonic force constants. Especially, the correction term included in the effective intramolecular potential function which is assumed in the model is expanded in the analytic form of an inverse power series of the bonded and non-bonded internuclear distances. The improved model is tested using some triatomic molecules (CO 2, CS 2, OCS, N 2O) whose experimental anharmonic force constants are presently available, and it is shown that the model is useful in discussing anharmonic force fields of more complicated polyatomic molecules.