Optical absorption spectra of finite systems from a conserving Bethe-Salpeter equation approach

TL;DR

This paper introduces a conserving Bethe-Salpeter equation method for calculating optical absorption spectra of finite systems, enabling self-consistent electron-hole correlation analysis with potential applications to nanoclusters.

Contribution

The paper develops a novel conserving linear response approach based on the Bethe-Salpeter equation for finite systems, emphasizing self-consistency and scattering effects.

Findings

Successfully applied to Na clusters, demonstrating accurate spectra.

Highlights the significance of scattering and dephasing in optical responses.

Provides a framework for self-consistent electron-hole correlation calculations.

Abstract

We present a method for computing optical absorption spectra by means of a Bethe-Salpeter equation approach, which is based on a conserving linear response calculation for electron-hole coherences in the presence of an external electromagnetic field. This procedure allows, in principle, for the determination of the electron-hole correlation function self-consistently with the corresponding single-particle Green function. We analyze the general approach for a "one-shot" calculation of the photoabsorption cross section of finite systems, and discuss the importance of scattering and dephasing contributions in this approach. We apply the method to the closed-shell clusters Na_4, Na^+_9 and Na^+_(21), treating one active electron per Na atom.