Ab initio phonon coupling and optical response of hot electrons in plasmonic metals

TL;DR

This paper provides ab initio predictions of hot electron dynamics, electron-phonon interactions, and optical responses in plasmonic metals, enabling parameter-free interpretation of ultrafast laser experiments.

Contribution

It introduces first-principles calculations of electron-phonon coupling and dielectric response in plasmonic metals, revealing significant differences from previous models at high electron temperatures.

Findings

Significant deviations from free-electron models above 2000 K

First-principles dielectric response including interband and phonon-assisted transitions

Enhanced understanding of ultrafast laser probe signatures

Abstract

Ultrafast laser measurements probe the non-equilibrium dynamics of excited electrons in metals with increasing temporal resolution. Electronic structure calculations can provide a detailed microscopic understanding of hot electron dynamics, but a parameter-free description of pump-probe measurements has not yet been possible, despite intensive research, because of the phenomenological treatment of electron-phonon interactions. We present ab initio predictions of the electron-temperature dependent heat capacities and electron-phonon coupling coefficients of plasmonic metals. We find substantial differences from free-electron and semi-empirical estimates, especially in noble metals above transient electron temperatures of 2000 K, because of the previously-neglected strong dependence of electron-phonon matrix elements on electron energy. We also present first-principles calculations of the electron-temperature dependent dielectric response of hot electrons in plasmonic metals, including direct interband and phonon-assisted intraband transitions, facilitating complete theoretical predictions of the time-resolved optical probe signatures in ultrafast laser experiments.