Soft Sticky Dipole Potential for Liquid Water: A New Model

A new, efficient potential model for liquid water is presented here. It is based on the hard-sphere sticky dipole potential model for water by Bratko, Blum, and Luzar (J. Chem. Phys. 1985, 83, 6367), referred to as the BBL model. Similar to the BBL model, this new, soft-sphere sticky dipole model has a single interaction site at the molecular center of mass with a spherical repulsive potential, a short-range tetrahedral “sticky” potential, and a point dipolar potential. However, the use of a Lennard-Jones-type soft-sphere, as opposed to the hard-sphere in the BBL model, allows realistic studies of water and aqueous solvation. This is particularly important for the existing parametrizations of biological molecules that use soft-sphere models. The present model gives a liquid water structure comparable to that found by the four-site TIP4P model and also gives an intermolecular energy, a hydrogen bond energy, and a heat capacity of liquid water in good agreement with experimental data and/or results from the...