Developing Monovalent Ion Parameters for the Optimal Point Charge (OPC) Water Model

Abstract

Molecular dynamics (MD) simulations are used to model the structure and movement of macromolecules. The gold standard for MD is to explicitly include water molecules using one of several standard models. Recently, a new water model, Optimal Point Charge (OPC), has been developed with simulation performance that compares better to experiment than existing models in its class (Izadi, Anandakrishnan, Onufriev, J. Phys. Chem. Lett., 2014, 5, 3863‐3871). For this new water model to be useful, Lennard‐Jones (LJ) parameters must be developed for at least a few monovalent ions. In this study MD simulations were used to develop these parameters. Preliminary results are presented including: extensive convergence testing of Hydration Free Energy, Lattice Constants (LC), and first peak position of radial distribution functions (RDF's); as well as surfaces showing the dependence of the RDF and LC on various LJ parameters within the OPC water model.Support or Funding InformationNational Science Foundation awards 1058981 and 1039925.