We are using an accurate, explicitly polarizable model of water in computer simulations to examine solvent structure and behavior around a variety of solutes. Our goals are: to perform free energy, structure, and enthalpy calculations on aqueous solutions of molecules of several types, emphasizing simple model systems; to compare the results to experiment and the predictions of other models and theories; and to suggest any self-consistent improvements. Our hypothesis is that aqueous solvation can be described more accurately by including more of the physical features of water. It remains to be determined how these features are best represented mathematically and how gains in accuracy are offset by increases in computational time. Contrary to simple expectations about increasing hydrophobicity, successive methylation of ammonia does not yield a monotonic increase in the observed solvation free energies. Previous free energy calculations have not reproduced the trend in experimental values. With the polarizable water model, the calculated increases in hydrophobicity with methylation are closer to experimental values, although the trend in the observed solvation energies is still not reproduced. We rely on MidasPlus and the Computer Graphics Lab resources for the visualization of molecular conformations and configurations generated by energy minimization and during molecular dynamics simulations.
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