Novel Electron Correlation Methods: Multiconfigurational Density Functional Theory

This Small Business Innovation Research Phase I project will result in a multiconfiguratinal density functional approach to electronic structure problems that combines ab initio generalized valence bond (GVB) and restricted configuration interaction (RCI) techniques with density functional theory (DFT) methods. The GVB-RCI-DFT software will use the pseudospectral techniques of Schrodinger, INc.'s PS-GVB software to allow rapid calculations without loss of accuracy. In Phase I, Schrodinger researchers will write the software necessary to implement the proposed GVB-RCI-DFT method in PS-GVB's pseudospectral faramework, examine results from various functionals and hybrid parameters, and use the methods to perform some preliminary calculations of molecular properties to illustrate its feasibility, speed, and accuracy. Extensions of Becke's half-half and three-parameter methods thast employ densities from GVB-RCI wavefunctions in the density functional evaluation of the correlation energy will be examined, and various parameters for the properties of large molecules will be tested. Calculations of various properties of large molecules will be performed using medium and large basis sets, inlcuding bond dissociation energies, activation energies, heats of formation, conformational energy differences, and proton affinities. These results will be compared to experiment or to timing and accuracy obtained using less rapid or less accurate ab initio and DFT methods.