Development & Applications of Density Functional Methods

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Weitao Yang of Duke University is supported by the Chemical Theory, Models and Computational Methods program in the Chemistry Division to develop new electronic structure methods. Electronic structure calculations provide fundamental information about molecular structure and molecular interactions, with broad applications in science and engineering. Because of its efficiency and its good accuracy for many applications, density functional theory (DFT) is the method of choice for such calculations for large systems. There are, however, many important applications where current DFT methods do not give accurate results. This proposal aims to build on the insight and progress made recently in order to develop the next-generation density functional approximations for accurate and efficient determination of electronic structure of large systems that are found in biology, chemistry, physics, engineering and nano-science and technology.With various theoretical strategies, the research effort will focus on exploring the functional forms needed to approximate exact conditions with fractional charges and spins, following two complementary directions: (1) Constructing approximations from first-principles many-body theory, particularly via the pairing matrix fluctuation formulation and (2) Imposing known exact conditions in terms of fractional variables on commonly-used functionals. The functionals developed will be theoretically sound, and have minimal delocalization and static correlation errors. They will be accurate for a broad range of applications and advance the frontiers of DFT towards the correct descriptions of thermochemistry, reaction kinetics, charge transfer, organic and transition metal molecules to bulk materials. The research approach will be based on derivation from theory and physics, using the minimal number of parameters . The proposed work should contribute to the progress of theoretical and computational chemistry in becoming an equal partner with other more traditional fields of chemistry.