A Density-Consistent, Finite van der Waals Potential from Gaussian Atomic Densities

In force fields that use Gaussian atomic densities, finite charge distributions soften short-range electrostatics, yet the van der Waals interaction can remain a separate singular Lennard-Jones term. We show that the same Gaussian density that regularizes electrostatics also generates a finite dispersion damping function through the damped dipole-dipole tensor, while overlap-based forms provide a compatible finite exchange repulsion. The resulting Gaussian van der Waals potential, GVDW, has the form Uvdw = Urep - C6F(κr)/r6, recovering the dipole-dipole 1/r6 dispersion tail at long range. As a minimal proof of concept in a polarizable Gaussian-density water model, with only two O-O repulsive parameters refitted, GVDW gives stable liquid simulations and shifts the close-contact O-O radial distribution function toward experiment relative to the Lennard-Jones potential. The result suggests a route to nonbonded potentials organized around a common finite-density picture.