Contract W911NF-12-1-0573 (University of Texas at Austin)

Abstract

Abstract : In this project we focused on the development of theoretical techniques (primarily numerical) that could be used to study correlated topological phases where density functional theory (DFT) could not. The main tool we sought to develop is dynamical mean field theory (DMFT). In DMFT, the main object is the single-particle Green's function. Theoretical work independent of this project established formulas that express the topological properties in terms of the single-particle Greens functions. Thus, there is a direction connection between the quantities that DMFT can compute, and the topological properties of a material. The major technical challenge in DMFT is the so-called impurity solver. Our main result in this roughly 12-month project was to benchmark various methods of solving the DMFT problem: NCA, OCA, CT-QMC, and IPT. Certain methods are computationally cheaper, but less accurate. We identified some of the tradeoffs in the choices and brought the PI's group capability to the point where it can be applied to the study of strongly interacting topological phases.