Electronic and Optical Excitations in Confined Nanostructures*

Electronic and optical excitations in confined nanostructures have been in the center of an intense research effort for the last two decades. Achieving a detailed understanding of how light interacts with matter at the nanoscale and how it can be manipulated to tune material properties is a challenging endeavor that necessitates a reliably predictive modeling and simulation effort to aid and interpret experiments. To this end, computational work during the last two decades on time-dependent density-functional-theory (TDDFT) and Green’s function-based many-body perturbation theory methods, such as the GW approximation and the Bethe-Salpeter equation (BSE), have provided reliable methodologies to examine electronic and optical excited states from first principles within similar frameworks as ground state properties. This talk will focus on our recent applications of real-space TDDFT and GW-BSE methods to a variety of confined nanostructures. They include our studies on (i) the nature of electronic and optical excitations in bulk-truncated TiO₂ nanocrystals, (ii) the effects of self-consistency and vertex corrections in the GW-BSE formalism in predicting excitation spectra of a set of aromatic molecules, and (iii) comparison of predictions from density-functional, many-body perturbation, and quantum chemistry techniques for photoelectron spectra of small copper oxide and related transition metal oxide clusters.