Development of ions-TIP4P-Ew force fields for molecular processes in bulk and at the aqueous interface using molecular simulations

Monovalent ions such as alkalis and halides play essential roles in aqueous and biological systems; thus a proper representation of these ions is significant in explicit molecular dynamics simulations. In this study, we re-parameterize ion interaction potentials for alkali metal ions (Li+, Na+, K+, Rb+, Cs+) and for halides (F-, Cl-, Br-, I-) based on TIP4P-Ew water at 298 K. The experimental enthalpies of hydration were used to optimize the ion potential parameters. To validate the ion potential models, extensive molecular dynamics calculations were carried out to examine the bulk, interfacial, static structural and dynamical properties of the aqueous ionic solutions. These included radial distribution functions, angle distributions, velocity autocorrelation functions, diffusion coefficients, binding energies, mean residence time, surface potentials, and potentials of mean force. The computed results agreed with the available experimental data and observations. (C) 2012 Elsevier B.V. All rights reserved.