Dissipative Equation of Motion for Electromagnetic Radiation in Quantum Dynamics

Abstract

The dynamical description of the radiative decay of an electronically excited state in realistic many-particle systems is an unresolved challenge. In the present investigation electromagnetic radiation of the charge density is approximated as the power dissipated by a classical dipole, to cast the emission in closed form as a unitary single-electron theory. This results in a formalism of unprecedented efficiency, critical for ab-initio modelling, which exhibits at the same time remarkable properties: it quantitatively predicts decay rates, natural broadening, and absorption intensities. Exquisitely accurate excitation lifetimes are obtained from time-dependent DFT simulations for C 2+ , B + and Be, of 0.565, 0.831 and 1.97 ns respectively, in accord with experimental values of 0.57±0.02, 0.86±0.07 and 1.77-2.5 ns. Hence, the present development expands the frontiers of quantum dynamics, bringing within reach first-principles simulations of a wealth of photophysical phenomena, from fluorescence to time-resolved spectroscopies.

Radiative thermalization in semiclassical simulations of light-matter interaction

“…The density matrix is evolved in time according to the semiclassical dissipative equation of motion, truncated at first order, introduced in Ref. [18]:…”

“…Very recently, we have proposed a distinct semiclassical approach that considers the electromagnetic radiation of the electron charge density as originating from a classical dipole, allowing for a first-principles Lagrangian derivation of a dissipative equation of motion where emission is cast in closed form as a unitary single-electron theory [18]. This formalism, which is directly suitable for ab initio implementations, quantitatively reproduces a number of experimental observations including decay rates, natural broadening, and absorption intensities.…”

“…This formalism, which is directly suitable for ab initio implementations, quantitatively reproduces a number of experimental observations including decay rates, natural broadening, and absorption intensities. In the context of time-dependent density functional theory simulations, it yielded excited state lifetimes in atoms and ions with an accuracy within the error of experiments [18]. Here we investigate its performance in the description of thermal electromagnetic radiation.…”

Semiclassical Real-Time Nuclear-Electronic Orbital Dynamics for Molecular Polaritons: Unified Theory of Electronic and Vibrational Strong Couplings

“…Other methods such as the exact factorization and multiconfigurational time-dependent Hartree method (MCTDH) also provide an accurate description of quantum effects under ESC or VSC. In addition to a fully quantum or classical treatment of the coupled cavity-molecular system, a variety of semiclassical treatments of the light–matter system − have also been shown to have the potential to accurately predict many light-involved processes from weak coupling to ESC.…”

Semiclassical Real-Time Nuclear-Electronic Orbital Dynamics for Molecular Polaritons: Unified Theory of Electronic and Vibrational Strong Couplings

“…Other methods such as the exaction factorization 41 and multiconfigurational time-dependent Hartree method (MCTDH) 27 also provide an accurate description of quantum effects under ESC or VSC. In addition to a fully quantum or classical treatment of the coupled cavity-molecular system, a variety of semiclassical treatments of the light-matter system [42][43][44][45][46][47][48] have also been shown to have the potential to accurately predict many light-involved processes from weak coupling to ESC.…”