title: Defining Condensed Phase Reactive Force Fields from ab Initio Molecular Dynamics Simulations: The Case of the Hydrated Excess Proton.
abstract: In this report, a general methodology is presented for the parametrization of a reactive force field using data from a condensed phase ab initio molecular dynamics (AIMD) simulation. This algorithm allows for the creation of an empirical reactive force field that accurately reproduces the underlying ab initio reactive surface while providing the ability to achieve long-time statistical sampling for large systems not possible with AIMD alone. In this work, a model for the hydrated excess proton is constructed where the hydronium cation and proton hopping portions of the model are statistically force-matched to the results of Car-Parrinello Molecular Dynamics (CPMD) simulations. The flexible nature of the algorithm also allows for the use of the more accurate classical simple point-charge flexible water (SPC/Fw) model to describe the water-water interactions while utilizing the ab initio data to create an overall multistate molecular dynamics (MS-MD) reactive model of the hydrated excess proton in water. The resulting empirical model for the system qualitatively reproduces thermodynamic and dynamic properties calculated from the ab initio simulation while being in good agreement with experimental results and previously developed multistate empirical valence bond (MS-EVB) models. The present methodology, therefore, bridges the AIMD technique with the MS-MD modeling of reactive events, while incorporating key strengths of both.
authors.affiliation: Department of Chemistry, James Franck Institute, and Computation Institute, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States, and Center for Biophysical Modeling and Simulation and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.
authors.forename: Chris
authors.initials: C
authors.lastname: Knight
authors.affiliation: Department of Chemistry, James Franck Institute, and Computation Institute, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States, and Center for Biophysical Modeling and Simulation and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.
authors.forename: C Mark
authors.initials: CM
authors.lastname: Maupin
authors.affiliation: Department of Chemistry, James Franck Institute, and Computation Institute, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States, and Center for Biophysical Modeling and Simulation and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.
authors.forename: Sergei
authors.initials: S
authors.lastname: Izvekov
authors.affiliation: Department of Chemistry, James Franck Institute, and Computation Institute, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States, and Center for Biophysical Modeling and Simulation and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Voth