The remaining frozen terms, included as K 0 [ρ 0 ] in Equation , account for Pauli repulsion of frozen electron densities as well as higher order correlational effects such as attractive London Dispersion forces. Because we are using explicit atomic densities and point nuclei, density overlap effects are also accounted for in E frz that are not normally present in point charge force fields. Charge penetration effects contribute an overall attractive energy to E frz when overlap is small, causing the relative magnitude of all energy contributions from a traditional 12-6 Lennard-Jones potential to be too small in comparison to the total electrostatic energy.