The AMOEBA 2.0 Force Field: Calibration Against Ab Initio Calculations

Jay W. Ponder
Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA.
Contact : ponder@dasher.wustl.edu
Mercredi 30 Mars 2016, 14h00
bibliothèque LCT, tour 12 - 13, 4^ème étage

The AMOEBA (Atomic Multipoles Optimized for Biomolecular Simulations) force field is intended for use in free energy calculations, drug design, materials science and other application areas where chemical accuracy is required of energies and forces. The model uses distributed multipole moments through quadrupoles and damped induced dipole moments to treat permanent electrostatics and polarization, respectively. Examples related to protein structure,ion and small molecule solvation, and interaction free energies will be described.

In an attempt to further refine the AMOEBA force field, we are calibrating individual components of the nonbonded interaction energy against various ab initio calculations, particularly SAPT results. Charge penetration (CP) is shown to be an important missing term arising from the use of point multipoles. Inclusion of a CP term results in excellent agreement between AMOEBA and the SAPT electrostatic term. A next step is modeling of the SAPT induction energy against AMOEBA. Here, we find that the AMOEBA polarization energy to be generally too small in magnitude compared to SAPT induction. The difference may be most easily ascribed to charge transfer. We are currently exploring methods for a consistent description of polarization and charge transfer within the AMOEBA model.