Adiabatic approximation in time-dependent reduced-density-matrix functional theory

Ryan Requist*, Oleg Pankratov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

With the aim of describing real-time electron dynamics, we introduce an adiabatic approximation for the equation of motion of the one-body reduced density matrix (one-matrix). The eigenvalues of the one-matrix, which represent the occupation numbers of single-particle orbitals, are obtained from the constrained minimization of the instantaneous ground-state energy functional rather than from their dynamical equations. The performance of the approximation vis-à-vis nonadiabatic effects is assessed in real-time simulations of a two-site Hubbard model. Due to Landau-Zener-type transitions, the system evolves into a nonstationary state with persistent oscillations in the observables. The amplitude of the oscillations displays a strongly nonmonotonic dependence on the strength of the electron-electron interaction and the rate of variation of the external potential. We interpret an associated resonance behavior in the phase of the oscillations in terms of "scattering" with spectator energy levels. To clarify the motivation for the minimization condition, we derive a sequence of energy functionals Ev(n), for which the corresponding sequence of minimizing one-matrices is asymptotic to the exact one-matrix in the adiabatic limit.

Original languageAmerican English
Article number042519
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Volume81
Issue number4
DOIs
StatePublished - 26 Apr 2010
Externally publishedYes

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