The Exact Exchange-Correlation Potential in Time-Dependent Density Functional Theory: Choreographing Electrons with Steps and Peaks

Abstract

The time-dependent exchange-correlation potential has an unusual task in directing fictitious noninteracting electrons to move with exactly the same probability density as true interacting electrons. This has intriguing implications for its structure, especially in the non-perturbative regime, leading to step and peak features that cannot be captured by bootstrapping any ground-state functional approximations. We review what has been learned about these features in the exact exchange-correlation potential in time-dependent density functional theory in the past decade or so, and implications for the performance of simulations when electrons are driven far from any ground-state.