Time-dependent schrödinger equation approach and bethe-salpeter equation approach

Abstract

In this article, I will compare two different first-principles methods useful in the research of clusters and nanoscale materials. The first one is the time-dependent Schrödinger equation approach for chemical reactions or light harvesting functions in excited states, and the second one is the Bethe-Salpeter equation approach for photoabsorption spectra, exciton wavefunctions, double-ionization energy spectra, and two-electron distribution functions, I will newly derive some exact theorems related to these approaches. While the first approach is convenient and useful, the second approach, which satisfies Friedel sum rule, is more reliable and accurate. © 2007 Society of Nano Science and Technology.