Electromagnetic radiation in first-principles electron dynamics: an equation story

DAMIAN A SCHERLIS

Trieste

Workshop; Workshop on Frontiers in Excited State Electronic Structure Methods: from Spectroscopy to Photochemistry; 2023

ICTP

Electron dynamics simulations ofatomic and molecular systems ignore in most cases an importantphenomenon: radiative dissipation. Spontaneous emission, or theradiative decay of an excited electronic state, is typically absentfrom quantum dynamics modelling. As a consequence, the energyabsorbed during the excitation of a molecule at zero temperature willremain in the system in the form of undamped dipole oscillations,indefinitely in time. Wehave addressed this problemstarting fromthe idea that the electromagnetic radiation of the charge density canbe approximated as the power dissipated by a classical dipole. Thisstrategy leads to a semiclassical equation of motion that reproducesradiative emission in a simple way, providing a first-principlesformalism that quantitatively captures decay rates, naturalbroadening, and absorption intensities [1].The implementation of this theoryin real time TDDFT simulations produces accurate excitation lifetimesfor atomic species. Furthermore,its application to thedescription of cooperative emission in H2arrays predictssuperradiant and subradiant behavior, unveilingthe relationbetween spatial configuration anddecoherence and how the fine-tuning of a pulse canaccumulate or releaseoptical energy in molecularassemblies[2].[1]Phys. Rev. Lett. 126,087401 (2021).[2]J. Phys. Chem.Lett. 13,11601 (2022).p { margin-bottom: 0.1in; direction: ltr; color: #000000; line-height: 115%; orphans: 2; widows: 2 }p.western { font-family: "Liberation Serif", "Times New Roman", serif; font-size: 12pt; so-language: en-US }p.cjk { font-family: "Noto Sans CJK SC"; font-size: 12pt; so-language: zh-CN }p.ctl { font-family: "Lohit Devanagari"; font-size: 12pt; so-language: hi-IN }