Statistical mechanics of small chain molecular liquids. I. Conformational properties of modeled n-butane

Abstract

The density functional formalism can also be profitably applied to the statistical mechanics of molecular fluids with internal degrees of freedom. The change of the intrinsic chemical potential for different conformers of nonpolar molecules is given by a zeroth order perturbation approach. This approach is applied to study the isomerization of n-butane in liquids, which models the neat liquid and CCl4 solutions. We find that a nonpolar solvent medium produces a shift in the conformational equilibria of model liquid n-butane from that found in the gas phase. The theoretical predictions show a good agreement with recent Monte Carlo and molecular dynamics simulations results. Discrepancies with Jorgensen et al.’s data are explained in terms of the attractive intermolecular forces used in their MC codes.