CHARMM Drude polarizable force field parameter development for model compounds representative of biological systems

COMP 213

Igor V. Vorobyov, vorobyov@outerbanks.umaryland.edu, Victor M. Anisimov, victor@outerbanks.umaryland.edu, and Alexander D. MacKerell Jr., alex@outerbanks.umaryland.edu. Department of Pharmaceutical Sciences, University of Maryland, 20 Penn Street, Room 601, Baltimore, MD 21201
Development of Drude polarizable force field parameters for use in the program CHARMM was performed for small molecules representative of the building blocks of biomolecular systems. Model systems included alkanes and neutral polar compounds. The partial atomic charges and atomic polarizabilities were determined via restrained fitting to perturbed QM electrostatic potential maps. The internal and Lennard-Jones parameters were determined based on the reproduction of the experimental and/or high-level QM geometric, energetic and thermodynamic gas- and condensed-phase properties. Additive CHARMM27 all-atom force field parameters were used as an initial guess for the Drude polarizable force field development. The Drude polarizable model shows an improvement in the treatment of selected gas- and condensed-phase electrostatic properties such as the static dielectric constant and dipole moment. These improvements allow for a more accurate description of the molecular behavior in both polar and non-polar environments by the Drude polarizable CHARMM force field.