J. Richardi et al., Influence of the intermolecular electrostatic potential on properties of polar polarizable aprotic solvents, MOLEC PHYS, 96(9), 1999, pp. 1411-1422
The liquid properties of models of acetonitrile, acetone and chloroform are
calculated within the framework of the hypernetted chain approximation of
the molecular Ornstein-Zernike theory. The shape of a molecule is described
by a set of Lennard-Jones sites. Its electrostatic properties are modelled
either by the first multipole moments up to the octopole or by partial cha
rges, and by a point polarizability tensor. The multipole moments and the p
artial charges are computed by ab initio molecular orbital methods. In the
liquid phase, the polarizability is taken into account by calculating an ef
fective induced point dipole moment using a self-consistent mean-field appr
oximation. While the Lennard-Jones part of the internal excess energy is ne
arly independent of the description of the electrostatic interaction and of
the polarizability, the electrostatic part and the dielectric constant cha
nge notably. The models with the partial charges lead to dielectric constan
ts which are in good agreement with the experimental data, provided that th
e molecular polarizability is correctly taken into account. The internal ex
cess energies are also correctly predicted except for acetone. How the appr
oximation of the intermolecular electrostatic interaction modifies the liqu
id structure is studied by investigating the dominant bimolecular configura
tions. These configurations allow one to understand better why the Kirkwood
factor changes with the electrostatic description. The Ornstein-Zernike fo
rmalism is a practical tool for studying with light numerical effort how th
e liquid properties depend on the intermolecular interaction. It can help i
n the development of new accurate potentials for liquid simulation.