Beyond traditional effective intermolecular potentials and pairwise interactions in molecular simulation

Molecular simulation methods such as Monte Carlo simulation and both

equilibrium and nonequilibrium molecular dynamics are powerful computational

techniques that allow the exact calculation of molecular properties with minimal

approximations. The main approximations are the choice of intermolecular

potential and the number of particles involved in each interaction. Typically, only

pairwise interactions are counted using a simple effective intermolecular potential

such as the Lennard-Jones potential. The use of accurate two-body potentials and

calculations that explicitly include three or more body interactions are rare because

of the large increase in computational cost involved. Here, we report recent

progress in the use of both genuine two-body potentials and calculations involving

three-body interactions. We show that in some cases, the contribution of threebody

interactions can be accurately estimated from two-body interactions without

the increase in computational cost involved in explicitly accounting for three-body

interactions. As an example of the benefit of including three-body interactions, the

improvement in the prediction of vapour-liquid equilibria is examined.