Quantum memory effects on the dynamics of electrons in small gold clusters

TL;DR

This paper investigates how memory effects influence electron dynamics in small gold clusters using a time-dependent density functional theory with a novel memory term, revealing significant broadening of plasmon lines and effects on high harmonic generation.

Contribution

The study introduces a translationally invariant memory functional in TDDFT and applies it to gold clusters, demonstrating its impact on electron dynamics and optical properties.

Findings

Memory broadens surface plasmon absorption lines

Memory narrows high harmonic emission lines

Memory effects cause a fast decay followed by a slower tail in plasmon decay

Abstract

Electron dynamics in metallic clusters are examined using a time-dependent density functional theory that includes a 'memory term', i.e. attempts to describe temporal non-local correlations. Using the Iwamoto, Gross and Kohn exchange-correlation (XC) kernel we construct a translationally invariant memory action from which an XC potential is derived that is translationally covariant and exerts zero net force on the electrons. An efficient and stable numerical method to solve the resulting Kohn-Sham equations is presented. Using this framework, we study memory effects on electron dynamics in spherical Jellium 'gold clusters'. We find memory significantly broadens the surface plasmon absorption line, yet considerably less than measured in real gold clusters, attributed to the inadequacy of the Jellium model. Two-dimensional pump-probe spectroscopy is used to study the temporal decay profile of the plasmon, finding a fast decay followed by slower tail. Finally, we examine memory effects on high harmonic generation, finding memory narrows emission lines.