Excitonic effects in time-dependent density-functional theory: An analytically solvable model

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dc.creatorStubner, R.
dc.creatorTokatly, I. V.
dc.creatorPankratov, O.
dc.date2004-06-15
dc.date.accessioned2026-07-07T02:58:38Z
dc.date.available2026-07-07T02:58:38Z
dc.descriptionWe investigate the description of excitonic effects within time-dependent density-functional theory (TDDFT). The exchange-correlation kernel f_xc introduced in TDDFT allows a clear separation of quasiparticle and excitonic effects. Using a diagrammatic representation for f_xc, we express its excitonic part f_xc^Ex in terms of the effective vertex function Lambda. The latter fulfills an integral equation which thereby establishes the exact correspondence between TDDFT and the standard many-body approach based on Bethe-Salpeter equation (BSE).The diagrammatic structure of the kernel in the equation for Lambda suggests the possibility of strong cancellation effects. Should the cancellation take place, already the first-order approximation to f_xc^Ex is sufficient. A potential advantage of TDDFT over the many-body BSE method is thus dependent on the efficiency of the above-quoted cancellation. We explicitly verify this for an analytically solvable two-dimensional two-band model. The calculations confirm that the low-order f_xc^Ex perfectly describes the bound exciton as well as the excitonic effects in the continuous spectrum in a wide range of the electron--hole coupling strength.
dc.descriptionRevTeX 4, 12 pages, 13 figures
dc.identifierhttps://arxiv.org/abs/cond-mat/0406344
dc.identifierhttp://arxiv.org/abs/cond-mat/0406344
dc.identifierPhys. Rev. B 70, 245119 (2004)
dc.identifierdoi:10.1103/PhysRevB.70.245119
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/24181
dc.subjectOther Condensed Matter
dc.titleExcitonic effects in time-dependent density-functional theory: An analytically solvable model
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