Dresden 2026 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 37: Development of Calculation Methods I

MM 37.3: Vortrag

Donnerstag, 12. März 2026, 16:15–16:30, SCH/A315

Electron thermalization in TDDFT and Ehrenfest molecular dynamics — •Tobias Zier, Uday Panta, and David A. Strubbe — University of California, Merced, USA

A non-equilibrium electronic state will in general thermalize toward an equilibrium state due to electron-electron interactions as well as interactions with ions. The description of such processes has remained unclear and controversial in time-dependent density functional theory (TDDFT), given that the occupation numbers remain fixed over time and that adiabatic functionals do not include explicit dissipation. Nevertheless in the literature signs of thermalization to a Fermi-Dirac distribution have been found in effective occupations constructed by projection of the time-dependent wavefunctions onto the ground state. Key issues include whether this process is physical or an artefact, connection to the Eigenstate Thermalization Hypothesis, and the dependence on the density of states, external fields, and xc functionals. To shed light on these phenomena, we study explicit time propagation of graphene after ultrafast laser pulses, with the Octopus real-space code, with and without ionic motion in Ehrenfest molecular dynamics. We study oscillations and the approach to an effective Fermi-Dirac distribution as well as decay of off-diagonal density matrix elements. This work has implications for treatment of statistical mechanics in a TDDFT framework and the nature of time-dependence in xc functionals, as well as for practical calculations of light-matter interactions especially for strong fields as in laser fusion experiments leading to warm dense matter and plasmas

Keywords: TDDFT; Thermalization; Ultrafast laser; Ehrenfest dynamics