Chlorinated ethanes in aqueous solution: parameterization based on thermodynamics of hydration

Lennard-Jones parameters for short chain alkanes and chloroethanes were optimized in order to reproduce experimental absolute hydration free energy data. Absolute solvation free energies were calculated using the recently developed separation-shifted scaling method in conjunction with thermodynamic integration calculations. Coefficients for the repulsive interaction of carbon, hydrogen, and chlorine with SPC/E water were optimized in order to simultaneously improve the agreement between calculated and experimental absolute hydration free energies for both unsubstituted short chain alkanes and chloroethanes. However, the optimized parameters resulted in substantially poorer agreement for pure liquid densities of chloroethanes.