Electron charge dynamics and charge separation: A response theory approach

In this talk, I will discuss the dynamics of excited electron charge through response theory, focusing on the strengths and limitations of linear response theory in capturing charge separation phenomena. To deepen our understanding of charge dynamics, I examine the impact of quadratic response, proposing efficient computational approximations for the second-order response function. Additionally, I explore the role of Coulomb interactions in modulating charge dynamics and separation. Our analysis includes a comparison between predictions from response theory and exact time propagation, using a model site-based system that emulates the behavior of a photovoltaic cell or diode.