Over the last decades non-polarizable force field methods have been very successful for treating many biological and condensed phase systems. Electrostatic interactions are essential in biological systems for structure, function, and protein-ligand interactions etc. It is known that polarization accounts for a significant part of the total energy (~15%) and is especially important for hydrogen bonding and ion interactions (see examples in the figure).We are here presenting results obtained with the polarizable OPLS-AAP force field applied to free energy perturbation calculations of protein-ligand complexes and molecular interactions with graphene, carbon nanotubes, and buckyballs. The polarizable OPLS-AAP force field was obtained from OPLS-AA by adding inducible dipoles calculated for each non-hydrogen atom in the presence of the electric field generated by the permanent force field charges. The OPLS-AAP force field was then optimized to yield good agreement with high-level quantum calculations for a large set of molecular complexes. The importance of polarization is illustrated in the figure. For example, the potassium ion has virtually no interaction energy with the buckyball, but by including polarization the interaction energy becomes 15.11 kcal/mol.

Polarizable force field OPLS-AAP applied to proteins and carbon surfaces

245th National Meeting (2013)

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