This project will advance the ability of quantum chemistry calculations to predict many important chemical, biological, and materials processes involving transition metals. Currently, quantum chemistry software is hampered in this task by a poor integration of ligand field theory and other basic concepts of inorganic chemistry. In this SBIR project, Schrodinger, Inc. will improve its electronic structure software package, PS-GVB, to allow users to incorporate their chemical intuition about organometallic systems and to make automated, intelligent selections of electronic properties that are not userspecified. The software will account for the effects of ligand fields, oxidation states, formal charges on ligands, and intrinsic properties of metals, producing a high-quality trial wavefunction for ab initio or density functional theory (OFT) calculations. In Phase II, Schrodinger, Inc. will make the technologies developed in Phase I available to non-expert users by incorporating the methods into an expert system graphical user interface. The software will allow the user full graphical control over the selection of specific electronic states of organometallic complexes. This flexibility will make electronic structure software widely useful for studies of molecular properties and excited states of systems containing transition metals.