The small unit cell reconstructions of SrTiO3(1 1 1)

Laurence D. Marks*, Ann N. Chiaramonti, Fabien Tran, Peter Blaha

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

We analyze the basic structural units of simple reconstructions of the (1 1 1) surface of SrTiO3 using density functional calculations. The prime focus is to answer three questions: what is the most appropriate functional to use; how accurate are the energies; what are the dominant low-energy structures and where do they lie on the surface phase diagram. Using test calculations of representative small molecules we compare conventional PBE-GGA with higher-order methods such as the TPSS meta-GGA and on-site hybrid methods PBE0 and TPSSh, the later being the most accurate. There are large effects due to reduction of the metal d oxygen sp hybridization when using the hybrid methods which are equivalent to a dynamical GGA + U, which leads to rather substantial improvements in the atomization energies of simple calibration molecules, even though the d-electron density for titanium compounds is rather small. By comparing the errors of the different methods we are able to generate an estimate of the theoretical error, which is about 0.25 eV per 1 × 1 unit cell, with changes of 0.5-1.0 eV per 1 × 1 cell with the more accurate method relative to conventional GGA. An analysis of the plausible structures reveals a new low-energy TiO2-rich configuration with octahedral co-ordination. This structure can act as a template for layers of either TiO or Ti2O3, consistent with experimental results. The results also suggest that both the fracture surface and the stoichiometric SrTiO3(1 1 1) surface should spontaneously disproportionate into SrO and TiO2 rich domains.

Original languageEnglish (US)
Pages (from-to)2179-2187
Number of pages9
JournalSurface Science
Volume603
Issue number14
DOIs
StatePublished - Jul 15 2009

Keywords

  • DFT
  • Polar oxide surfaces
  • Surface structure

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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