A simple model for the intermolecular potential of water

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Abstract
A simple potential for the pair interaction of two water molecules is proposed. This model is intended for use in ionic solvation problems, and is a step beyond the ion dipole model proposed by Adelman, Deutch, and Blum to study molecular effects in solvation. It consists in adding to the hard spheres with a point dipole a narrow potential well with a tetrahedral octupole of the form v(θ,φ)=A(r)sin θ sin 2θ cos 2φ. We test this potential and two improvements by running a Monte Carlo simulation on a system of 70 molecules. The results show that our model reproduces surprisingly well the essential features of the structure of water, namely the rather well defined tetrahedral structure of the first coordination shell, and the very poorly structured second and third coordination shells.