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Titolo: Densityfunctional modelling of corehole effects in electron energyloss nearedge spectra
Autore: Elsasser, C; Kostlmeier, S;
 Indirizzi:
 Max Planck Inst Met Forsch, D70174 Stuttgart, Germany Max Planck Inst MetForsch Stuttgart Germany D70174 Stuttgart, Germany
 Titolo Testata:
 ULTRAMICROSCOPY
fascicolo: 34,
volume: 86,
anno: 2001,
pagine: 325  337
 SICI:
 03043991(200102)86:34<325:DMOCEI>2.0.ZU;2S
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 XRAYABSORPTION; GROUNDSTATE PROPERTIES; FINESTRUCTURE; LOSS SPECTROSCOPY; MANYELECTRON; METALS; TIS2; MGO;
 Keywords:
 density functional theory; bandstructure calculations; magnesium oxide; electron energy loss spectroscopy; energyloss nearedge structures; corehole effects;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Life Sciences
 Physical, Chemical & Earth Sciences
 Citazioni:
 24
 Recensione:
 Indirizzi per estratti:
 Indirizzo: Elsasser, C Max Planck Inst Met Forsch, Seestr 92, D70174 Stuttgart, Germany Max Planck Inst Met Forsch Seestr 92 Stuttgart Germany D70174



 Citazione:
 C. Elsasser e S. Kostlmeier, "Densityfunctional modelling of corehole effects in electron energyloss nearedge spectra", ULTRAMICROS, 86(34), 2001, pp. 325337
Abstract
A series of (MgO)(n) supercells (n = 1,4, 8, 16, 32) with threedimensional periodic boundary conditions is investigated by densityfunctional bandstructure calculations. The influence of supercell size and shape on calculated electron energyloss nearedge spectra is assessed quantitatively, employing the Z + 1 approximation for the representation of finalstate effects. Relevant convergence criteria are the length scale set by the spatial extension of the valenceelectron screening cloud around the core hole and theinteraction energy of neighbouring corehole centres. A sufficient supercell size provided, the Z + 1 approximation yields a highly satisfactory description of excitations from the Is shell of light elements, such as Mg and O, compared to experimental data. For comparison, pseudopotentials for excited states were generated for Mg, both with a large core (Is, 2s, 2p orbitals) and a small core (Is orbital only) included into the pseudopotential. The corresponding calculations with frozen core holes lead to very good agreement with the results from the Z + 1 calculation for the Is excitations. The explicit treatment of the subvalence shell (2s, 2p), however, is mandatory for the proper modelling of excitations from orbitals higher than 1s. This indicates that the core polarisability plays an important role in excitations from more extended shells. (C) 2001 Elsevier Science B.V. All rights reserved.
ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 26/09/20 alle ore 05:32:49