Revised charge equilibration parameters for more accurate hydration free energies of alkanes

We present a refined alkane charge equilibration (CHEQ) force field, improving our previously reported CHEQ alkane force field [1] to better reproduce experimental hydration free energies. Experimental hydration free energies of ethane, propane, butane, pentane, hexane, and heptane are reproduced to within 3.6% on average. We demonstrate that explicit polarization results in a shift in molecular dipole moment for water molecules associated with the alkane molecule. We also show that our new parameters do not have a significant effect on the alkane-water interactions as measured by the radial distribution function (RDF). (C) 2009 Elsevier B.V. All rights reserved.