Simulating Solvent Effects and Liquid Behavior with the Effective Fragment Potential Method

Heather Netzloff, Iowa State University

As the size of a system grows, ab initio quantum chemistry calculations quickly increase in computational cost. In order to accurately model liquids and solvation effects, a large number of molecules are required. The Effective Fragment Potential (EFP) method for solvation has been developed, in part, to address these concerns. In the method, the system is divided into an ab initio region that contains the solute plus some number of solvent molecules, if desired, and an ‘effective fragment’ region that contains the remaining solvent molecules. Interaction between solvent molecules, represented by effective fragments, and the ab initio part of the system is treated via one- electron terms; fragment-fragment interactions are treated in a similar manner. Thus, the total system Hamiltonian is a sum of the ab initio Hamiltonian and the potential due to the fragment interactions. The potential includes Coulomb, polarization (self-consistent induced dipole), and exchange repulsion + charge transfer terms to describe the interaction. Several of my research projects utilize EFP, including coupling of EFP and molecular dynamics and parallelization of the EFP code within GAMESS. In both cases our aim is to test and use the EFP approach to extend our capabilities to larger systems and model bulk behavior.

Abstract Author(s): Heather M. Netzloff and Mark S. Gordon