Plasmon Lifetime in K: A Case Study of Correlated Electrons in Solids Amenable to Ab Initio Theory

TL;DR

This paper introduces an ab initio approach within time-dependent density-functional theory to accurately analyze plasmon linewidths in potassium, revealing the decay mechanisms involving d-symmetry states and emphasizing the role of electron correlations.

Contribution

It presents a novel ab initio, all-electron response scheme for studying plasmon damping in correlated-electron systems, highlighting the importance of final-state d-bands.

Findings

Decay into particle-hole pairs involving d-symmetry states is the main damping mechanism.

Many-particle correlations have a small overall effect, but final-state d-bands are crucial.

The approach successfully explains the anomalous plasmon linewidth dispersion in potassium.

Abstract

On the basis of a new ab initio, all-electron response scheme, formulated within time-dependent density-functional theory, we solve the puzzle posed by the anomalous dispersion of the plasmon linewidth in K. The key damping mechanism is shown to be decay into particle-hole pairs involving empty states of d-symmetry. While the effect of many-particle correlations is small, the correlations built into the "final-state" -d-bands play an important, and novel, role ---which is related to the phase-space complexity associated with these flat bands. Our case study of plasmon lifetime in K illustrates the importance of ab initio paradigms for the study of excitations in correlated-electron systems.