CAREER: Finite Temperature Electronic Structure Methods for Predicting Material Phase Diagrams

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Brenda Rubenstein of Brown University is jointly funded by the Chemical Theory, Models and Computational Methods program in the Division of Chemistry, and the Established Program to Stimulate Competitive Research (EPSCoR) to develop new methods for modeling the finite temperature electronic properties of correlated materials. In applications ranging from catalysis to astrophysics to material science, molecules and materials can be subjected to high temperatures. Nevertheless, relatively few theories exist to predict how these materials will behave at such temperatures,thwarting our ability to engineer materials such as high-Tc superconductors and next-generation thermally-responsive technologies. As part of this project, the Rubenstein Group will develop a suite of complementary theories and simulation techniques that will enable the high-accuracy modeling of complex materials at finite temperatures. In addition to this research, the Rubenstein Group will bolster its ongoing efforts to actively mentor historically-underrepresented high school students in Rhode Island through the science fair process via the Rhode Island American Chemical Society Project SEED and Advocate Programs (which Dr. Rubenstein leads) and grant area high school students opportunities to engage in real experiments through the Brown University Chemistry Department’s STEM Day Program. Dr. Rubenstein also is developing a new Accelerating Chemical Discovery course and related textbook with the aim of familiarizing undergraduates in the chemical sciences with how data science can be leveraged to solve everyday problems in chemistry.The central aim of this proposal is to develop a suite of new finite temperature electronic structure techniques to elucidate the electronic phase diagrams of correlated materials. In plasmonic catalysis, astrophysics, materials science, and many other applications, molecules and materials are subject to high temperatures at which their electrons populate a wide distribution of energy levels. Nevertheless, most electronic structure methods to date have focused on the ground state, and those methods that do account for temperature either do not accurately account for electron correlation or have overwhelmingly been developed to study lattice models that do not capture the unique qualities of real materials. To rise to this challenge, the Rubenstein Group recently developed a new, fully ab initio, fully correlated finite temperature Auxiliary Field Quantum Monte Carlo (FT-AFQMC) method that proved to be able to yield exact results on a wide variety of benchmark molecules and simple solids. In this CAREER proposal, the Rubenstein Group aims to extend this technique to the study of heavier materials, including iron oxide, nickel oxide, vanadium oxide, and chromium triiodide, whose finite temperature electronic phase transitions have yet to be fully understood, while also developing a set of novel supporting mean field, selected CI (configuration interaction), and sampling techniques. These will not only improve FT-AFQMC’s performance, but can also serve as cheaper, stand-alone methods in their own right.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.