Accurate and Precise Molecular Simulation Algorithms for Standard State Chemical Potentials and Activity Coefficients in Henry-Law Models of Electrolyte Solutions

Abstract

This thesis focuses on the development of a novel molecular simulation methodology to accurately calculate standard state chemical potentials and activity coefficients of electrolyte species for their ultimate implementation in thermodynamic models of liquid solutions. Molecular simulation is based on the use of simple mathematical forms (force fields) for the description of the forces among individual molecules. For this study, the macroscopic Henry-Law (infinite dilution ideality) model for the chemical potential is connected to a particular ensemble used in statistical mechanics. We use a little-known explicit form for this connection, which yields an avenue for the calculation of μ† and activity coefficients by means of molecular simulation. We developed a novel procedure to calculate μ† by extrapolation of residual chemical potentials obtained from molecular simulation to infinite dilution and allows for the subsequent calculation of lnγ. Results are presented here for the simple system of NaCl, but this methodology can be applied to any electrolyte system with only minor modifications.