Multipolar Force Fields for Atomistic Simulations

Abstract

We present the status and advances of the Gaussian Electrostatic Model (GEM) force field. GEM is a polarizable potential that relies on fitted molecular electronic densities to calculate intermolecular interactions. The philosophy of GEM is to separately account for each of the inter–molecular interaction contributions including Coulomb, exchange–repulsion, polarization, charge–transfer and dispersion. To evaluate each of these terms, GEM relies on fitted molecular electronic densities and molecular properties calculated with these densities. Recently, we have also developed hybrid force fields combining GEM with polarizable force fields. GEM* combines the Coulomb and exchange–repulsion terms from GEM with the polarization, van der Waals (modified) and bonded terms from AMOEBA. We have also introduced a multi–scale implementation denoted S/G–1 that combines GEM and SIBFA demonstrating the advantage of the incorporation of the electron density force field when applied to thedescription of metals in biomolecular systems. Overall, the GEM framework and its hybrid approaches offer a new strategy for molecular dynamics with enhanced accuracy at a cost that will enable the possibility of adequate sampling