Non-linear phenomena in time-dependent density-functional theory: What Rabi physics can teach us
Abstract
Through the exact solution of a two-electron system interacting with a monochromatic laser we prove that all adiabatic density functionals within time-dependent density-functional theory are not able to discern between resonant and non-resonant (detuned) Rabi oscillations. This is rationalized in terms of a fictitious dynamical exchange-correlation (xc) detuning of the resonance while the laser is acting. The non-linear dynamics of the Kohn-Sham system shows the characteristic features of detuned Rabi oscillations even if the exact resonant frequency is used. We identify the source of this error in a contribution from the xc-functional to the non-linear equations describing the electron dynamics in an effective two-level system. The constraint of preventing the detuning introduces a new strong condition to be satisfied by approximate xc-functionals.
Cite
@article{arxiv.1101.2880,
title = {Non-linear phenomena in time-dependent density-functional theory: What Rabi physics can teach us},
author = {J. I. Fuks and N. Helbig and I. V. Tokatly and A. Rubio},
journal= {arXiv preprint arXiv:1101.2880},
year = {2011}
}