Collective Excitations in the Classical One-Component Plasma at High Densities and Intermediate Wave Numbers

Density- and current-fluctuation spectra of a dense, classical one-component plasma are discussed within a simple model based on the mode-coupling theory of liquid dynamics. The appearance of a second high-frequency shear mode at intermediate wave numbers is explained in terms of a level repulsion effect between the bare transverse current mode and the two-mode excitation spectrum. The same interaction with the longitudinal current mode is responsible for a small additional high-frequency peak in the densityfluctuation spectrum.