Macroscopic and microscopic components of exchange-correlation interactions
2003 (engelsk)Inngår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 68, nr 20, s. 205112-205122, artikkel-id 205112Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]
We consider two commonly used approaches for the ab initio calculation of optical-absorption spectra, namely, many-body perturbation theory based on Green’s functions and time-dependent density-functional theory (TDDFT). The former leads to the two-particle Bethe-Salpeter equation that contains a screened electron-hole interaction. We approximate this interaction in various ways, and discuss in particular the results obtained for a local contact potential. This, in fact, allows us to straightforwardly make the link to the TDDFT approach, and to discuss the exchange-correlation kernel fxc that corresponds to the contact exciton. Our main results, illustrated in the examples of bulk silicon, GaAs, argon, and LiF, are the following. (i) The simple contact exciton model, used on top of an ab initio calculated band structure, yields reasonable absorption spectra. (ii) Qualitatively extremely different fxc can be derived approximatively from the same Bethe-Salpeter equation. These kernels can however yield very similar spectra. (iii) A static fxc, both with or without a long-range component, can create transitions in the quasiparticle gap. To the best of our knowledge, this is the first time that TDDFT has been shown to be able to reproduce bound excitons.
sted, utgiver, år, opplag, sider
American Physical Society, 2003. Vol. 68, nr 20, s. 205112-205122, artikkel-id 205112
Emneord [en]
density-functional theory, ab-initio calculation, inhomogeneous electron-gas, quasi-particle, greens-function, dielectric function, optical-absorption, hole interaction, excitations, semiconductors
HSV kategori
Identifikatorer
URN: urn:nbn:se:his:diva-1998DOI: 10.1103/PhysRevB.68.205112ISI: 000187314400024Scopus ID: 2-s2.0-2642534606OAI: oai:DiVA.org:his-1998DiVA, id: diva2:32274
Merknad
PHYSICAL REVIEW B: covering condensed matter and materials physics
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