Development of First-Pinciples Electronic Structure Approach for Studying Molecular Structures, Properties, and Reaction Mechanisms in Solution

Chang-Guo Zhan ofthe University ofKentucky is supported by an award from the Theory, Models and Computational Methods program to develop a first-principles electronic structure method accounting for solvent effects. It is very popular modeling the effect of solvent as a dielectric continuum reaction field while the solute is treated quantum mechanically. Many practical reaction field implementations represent the solvent polarization through an apparent surface charge distribution on the boundary ofthe solute cavity. However, quantum mechanical calculations usually lead to a tail ofthe wave function penetrating outside the cavity. The solute charge distribution outside the cavity produces an additional volume polarization to the reaction field. The PI and his research group are developing a generalized implementation of a unique reaction field method, known as the fully polarizable continuum model (FPCM), capable of accurately determining volume polarization, in addition to the commonly treated surface polarization, for a general, irregularly-shaped solute cavity. In particular, they are developing the analytic energy derivatives with respect to the nuclear coordinates ofthe solute for the FPCM method so that the FPCM implementation can be used for the geometry optimization and vibrational frequency calculations on molecules in solution. In addition, they make use ofthe generalized implementation together with other available computational methods to study some representative chemical problems concerning molecular structures, properties, and reaction mechanisms. The broader impacts ofthis research are the applications ofthe generalized FPCM implementation to first-principles computational studies ofmolecular structures, properties, and reaction mechanisms in a wide range ofdisciplines such as inorganic chemistry, organic chemistry, biochemistry, environmental chemistry, medicinal chemistry, and pharmaceutical sciences.