ITR: Development of Computational Time-Dependent Density-Functional Theory Methods for the Study of Electronic Excitations in Correlated Materials

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This award under the Information Technology Research initiative supports fundamental computational and theoretical research, including algorithm development, on dynamical correlations in materials. Methods to be explored include time-dependent density functional theory (TDDFT) and Baym-Kadanoff conserving approximations.An aim of this work is to establish a synergy between novel computational methods and insight into the dynamical electronic correlations in non-trivial solid-state archetypes involving insulators, transition metals, rare-earth metal hydrides, and transition-metal oxides. Dynamical charge-density and spin density response functions will be calculated; these quantities map directly into experimental loss functions, and contain unique signatures of correlation. The time-dependent optimized-potential method will be implemented. This method, which relies on a representation of the exchange-correlation potential as a functional of one-electron orbitals, is self-interaction free. So, it represents a promising approach for the study of correlated materials. "Hybrid functionals," which have proved successful in the description of the ground state of antiferromagnetic insulators will also be explored. TDDFT will also be implemented without invoking the linear-response regime, by explicitly solving the time-dependent Kohn-Sham equation on a real-space grid, propagating the states on a time grid. Baym-Kadanoff conserving approximations will also be implemented and explored.The proposed theoretical and computational will contribute to the education of graduate students and postdocs in modern computational materials physics. College students from disadvantaged backgrounds will be actively recruited for research participation during the summers through the Ronald McNair program at UTK. %%%This award under the Information Technology Research initiative supports fundamental computational and theoretical research, including algorithm development on dynamical electronic correlations in insulators, transition metals, rare-earth metal hydrides, and transition-metal oxides. The work involves the development of new computational methods and the exploration of sophisticated theoretical formalism with an aim to forge a quantitative theory of electron dynamics and transport in real materials. The work will also contribute theoretical guidance to concurrent experimental investigations of materials using inelastic x-ray scattering. While this is fundamental research, the computational methods developed may support future advances in materials and optoelectronic device technologies.***