Capturing Nonlocal Correlations in Electronic Systems - Two-Particle Response and Parquet Equations

Explore the theoretical foundations and computational methods for understanding two-particle response functions in correlated electronic materials through this 53-minute physics colloquium. Learn what two-particle correlations are and when they become crucial in electronic systems, with particular emphasis on susceptibilities and optical conductivity as key quantities connecting theoretical predictions with experimental observations. Discover diagrammatic methods for computing these correlations and examine specific results for two-particle vertex corrections to optical conductivity in systems exhibiting antiferromagnetic or charge density wave fluctuations. Understand how these corrections lead to displaced Drude peaks in correlated metals and gain insights into the computational challenges involved in calculating nonlocal electronic correlations. Delve into recent methodological developments including the efficient representation of two-particle correlation functions using quantics tensor trains, providing new approaches to tackle complex many-body problems in condensed matter physics.