Evolution of the optical properties of alkali-metal microclusters towards the bulk: The matrix random-phase-approximation description

Abstract

The evolution toward the bulk values of the energy centroid and of the width characterizing the surface-plasmon resonance in spherical neutral sodium clusters is studied. For this purpose, the photoabsorption spectrum of clusters comprising from 8 to 338 atoms is calculated microscopically making use of the jellium shell model to describe the motion of delocalized electrons and of the matrix random-phase approximation to determine the collective response of the system to electromagnetic radiation. The Coulomb force is treated in the local-density approximation. The case of large potassium clusters having approximately 500 and 900 atoms is also considered.