Separability between valence and conduction bands in transition metal clusters

Edoardo Aprà, Emily A. Carter, Alessandro Fortunelli

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Simplified theories of transition metal electronic structure have been postulated for many decades. We test one such approximation, namely separate treatments of d (valence) and s/p (conduction) electrons in transition metal clusters, within a density functional theory (DFT) formalism. Two different basic approaches are considered: (a) an independent-band approximation, in which the d- and s/p-bands interact only via the p-dependent components of the Kohn-Sham operator; and (b) a more realistic approximation, in which the lowest-energy d- and s/p-orbitals (separately derived) are allowed to interact through explicit off-diagonal coupling matrix elements. The results are presented for the energy differences among three structural forms (icosahedral, cuboctahedral, and truncated decahedral) of 13-atom Ni and Pt clusters. We demonstrate that an explicit decoupling of the d- and s/p-bands does not produce accurate results for the clusters considered, not even for nickel, i.e., the transition metal for which d-s/p mixing should be at its minimum. By contrast, allowing the lowest-energy orbitals of the two separate bands to interact improves the results considerably, and ensures a fair description of metal-metal bonding. This finding suggests that simplified models that exclude explicit d-s/p coupling should be employed with caution.

Original languageEnglish (US)
Pages (from-to)277-287
Number of pages11
JournalInternational Journal of Quantum Chemistry
Volume100
Issue number3
DOIs
StatePublished - Nov 5 2004
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

Keywords

  • D-s hybridization
  • Electronic structure
  • Inter-band mixing
  • Structural energy differences
  • Transition and noble metals

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