A Polarizable Valence Electron Density Based Force Field for High-Energy Interactions between Atoms and Molecules

High-accuracy molecular force field models suited for hot gases and plasmas are not as abundant as those geared towards ambient pressure and temperature conditions. Here we present an improved version of our previous electron- density based force field model that can account for polarization effects by adjusting the atomic valence electron contri- butions to match ab initio calculated Mulliken partial charges. Using a slightly modified version of the Hohenberg-Kohn theorem, we also present an improved theoretical formulation of our model when dealing with systems with degenerate ground states. Preliminary results obtained from this methodology for water dimer calculations using CCSD(T)/cc- pVTZ and CCSD(T)/CEP-31G level of theory are presented using an order ten approximation. Further improvements include the additional interaction components with fictitious non-spherically symmetric, yet atom-centered, electron densities and fitting the exchange and correlation coefficients against analytical expressions. The latter removes all unphysical oscillations that are observed in the previous non-polarizable variant of our force field.