Fluctuation-Based Electronic Structure Methods

University Of California-Irvine, Irvine CA

Investigators

Abstract

Filipp Furche of the University of California, Irvine is supported by an award from the Chemical Theory, Models and Computational Methods Program in the Division of Chemistry to develop, implement, test, and apply novel computational chemistry methods. The Condensed Matter and Materials Theory program in the Division of Materials Research also contributes to this award. The new methods enable simulations of molecules and condensed matter systems that are very difficult to treat with conventional approaches, for example rare-earth compounds or transition metal compounds used in catalysis. Such systems are critically importance for science and emerging technologies. A fundamentally different approach to electronic structure theory based on quantum fluctuations, proposed by Furche promises to overcome many of these limitations. The methods developed in this project are made available to the public through the Turbomole quantum chemistry software. The project enhances undergraduate education and workforce readiness through a new concentration in Theoretical and Computational Chemistry at UCI and a high school outreach program aimed at students from disadvantaged backgrounds. Furche and his group are developing new methodology to enable predictive simulations of molecules and condensed matter systems such as small-bandgap or correlated materials and clusters, noncovalently bound nanostructures, or optical properties of transition-metal and rare earth compounds. Despite their critical importance for science and emerging technologies, these systems remain nearly intractable with conventional electronic structure methods, due to insufficient accuracy, computational efficiency, or both. Random phase approximation (RPA) methods developed during previous funding periods are the prototype fluctuation-based electronic structure theory. Guided by the successes and failures of RPA, Furche and his group are laying the groundwork for a systematically improvable hierarchy of electronic structure methods based on fluctuations. As opposed to the conventional approach to electron correlation in chemistry, which is based on interacting electron pairs, triples, etc., the methods proposed here describe correlation in many-electron systems by vacuum fluctuations generated by virtual pairs of electrons and holes traveling forward and backward in time (and multiples thereof). Furche and his group also explore a Brueckner functional framework as alternative to Kohn-Sham reference states, and aim to extend the scope of RPA methods to ionization, time-dependent properties, and excited states. Applications include low-valent rare-earth and actinide compounds, and halogen-pi interaction mediated drug design. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.