The Dependence of the Internal Vibrational Frequencies of Liquid Water on Central Force Potentials

Abstract

Abstract The differences in the liquid phase internal vibrational frequencies of water, obtained from molecular dynamics (MD) simulations, between the two versions of the central force model of Rahman and Stillinger (CF1 and CF2) are investigated by employing the theory of Buckingham on solvent effects. It is found that the differences can be essentially accounted for by the different O-H stretching cubic anharmonic force constants of CF1 and CF2. A significantly improved agreement between the results of MD simulations and spectroscopically observed liuqid phase frequencies could be achieved by using a harmonic force field, supplemented by a cubic stretching force constant, for the intramolecular interactions of water, and the CF2 potential for the intermolecular interactions.