Time-dependent exchange-correlation functional for a Hubbard dimer: Quantifying nonadiabatic effects
| Autor: | Heiko Appel, Ilya V. Tokatly, Mehdi Farzanehpour, Angel Rubio, Stefan Kurth, Johanna I. Fuks |
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| Rok vydání: | 2013 |
| Předmět: |
Chemical Physics (physics.chem-ph)
Physics education.field_of_study Work (thermodynamics) Rabi cycle Hubbard model Population FOS: Physical sciences 02 engineering and technology Time-dependent density functional theory 021001 nanoscience & nanotechnology 01 natural sciences Atomic and Molecular Physics and Optics 3. Good health Condensed Matter - Other Condensed Matter Nonlinear system Physics - Chemical Physics Quantum mechanics 0103 physical sciences Density functional theory 010306 general physics 0210 nano-technology Adiabatic process education Other Condensed Matter (cond-mat.other) |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname Physical Review A |
| ISSN: | 1094-1622 1050-2947 |
| DOI: | 10.1103/physreva.88.062512 |
| Popis: | We address and quantify the role of nonadiabaticity (“memory effects”) in the exchange-correlation (xc) functional of time-dependent density functional theory (TDDFT) for describing nonlinear dynamics of many-body systems. Time-dependent resonant processes are particularly challenging for available TDDFT approximations, due to their strong nonlinear and nonadiabatic character. None of the known approximate density functionals are able to cope with this class of problems in a satisfactory manner. In this work we look at the prototypical example of the resonant processes by considering Rabi oscillations within the exactly soluble two-site Hubbard model. We construct the exact adiabatic xc functional and show that (i) it does not reproduce correctly resonant Rabi dynamics, and (ii) there is a sizable nonadiabatic contribution to the exact xc potential, which turns out to be small only at the beginning and at the end of the Rabi cycle when the ground-state population is dominant. We then propose a “two-level” approximation for the time-dependent xc potential which can capture Rabi dynamics in the two-site problem. It works well both for resonant and for detuned Rabi oscillations and becomes essentially exact in the linear response regime. We acknowledge financial support from the European Research Council Advanced Grant DYNamo (Grant No. ERC-2010-AdG-267374), Spanish Grant (Grant No. FIS2010-21282-C02-01), Grupos Consolidados UPV/EHU del Gobierno Vasco (Grant No. IT578-13), and Ikerbasque and the European Commission projects CRONOS (Grant No. 280879-2 CRONOS CP-FP7). |
| Databáze: | OpenAIRE |
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