AB INITIO CALCULATION OF SOLVATION ENERGIES

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Wehavedevelopedanalgorithmforcarryingoutquantumchemical calculations in a dielectric medium. Our electronic structure program PSGVB first calculates electrostatic point charges using an ESP fitting method. These charges are then passed to DELPHI which determines the reaction filed by solving the Poisson-Boltzmann equation. The reaction field is represented as point charges on the dielectric boundary. These are passed to PSGVB which now solves quantum chemical equations in the field of the point charges. This process is iterated until self-consistency is reached. We have shown that if one uses accurate gas phase quantum chemical methods (GVB plus a good basis set is sufficient) solvation energies accurate to ~0.6kcal/mole can be computed for a test set of 29 molecules. Recent work includes development of an analytical gradient method using a novel finite element Poisson-Boltzmann solver and improvement of the accuracy of the continuum method via inclusion of corrections for short-range hydrogen bonding terms.