A Weeks–Chandler–Andersen based potential fitting procedure for molecular dynamics simulations of the calcite–water interface

We propose a standardized potential fitting procedure capable of producing cross-term parameters required by classical molecular dynamic (MD) simulations of aqueous-mineral systems where pure species parameters for water, solutes and mineral are known. Unlike other approaches, our technique keeps the original pure-species partial charges intact and provides the short-range part of potential in cases when direct application of standard combination rules is not feasible. The procedure is based on Weeks–Chandler–Andersen potential splitting method with Barker–Henderson integration and yields effective hard-sphere diameter used as one of the fitting criteria. A set of water-calcite interaction parameters was produced and applied to model behaviour of water near 101¯4 calcite surface by means of MD. The water structure was compared to both high-resolution XR data [1,2] and previous MD studies using various force fields [3–6]. Our simulations featuring fitted cross term parameters were found to be in general agreement with experimental data and proven more successful in matching water density profiles and ordering than previously utilized force field due to Hwang et al. [4,3].