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arXiv · 1101.2880

Non-linear phenomena in time-dependent density-functional theory: What Rabi physics can teach us

J. I. Fuks·N. Helbig·I. V. Tokatly·A. Rubio
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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.

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J. I. Fuks, N. Helbig, I. V. Tokatly, A. Rubio. 2011-01-14. Non-linear phenomena in time-dependent density-functional theory: What Rabi physics can teach us. https://doi.org/10.1103/physrevb.84.075107

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