On the simultaneous description of h‐bonding and dipolar interactions with point charges in force field models

Abstract

H‐bonding and polar interactions occur together in real fluids, but are of different nature and have different effects on macroscopic properties. Nevertheless, both are usually described by point charges in force field models. Despite this, the two effects can be separated. A simple model fluid is studied: a single Lennard‐Jones (LJ) site with two opposing point charges q placed in the center of the LJ site and at a distance d. By suitably varying both d and q, the dipole moment μ is kept constant. Both μ and d are systematically varied to study the properties of the resulting models, including H‐bonding, which is determined using a geometric criterion from literature. d can be used for tuning the H‐bonding strength and, thus, polarity and H‐bonding can be adjusted individually. The study of a second related model with symmetrically positioned point charges does not reveal this separation. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2926–2932, 2015