Bulk and Surface Properties of Rutile TiO2 from Self-Consistent-Charge Density Functional Tight Binding

• Published in: Journal of chemical theory and computation 2010-02, Vol.6 (2), p.499-507
• Main Authors: Fox, H, Newman, K. E, Schneider, W. F, Corcelli, S. A
• Format: Article
• Language: English
• Subjects: Condensed Matter, Interfaces, and Materials
• ISSN: 1549-9618; 1549-9626
• DOI: 10.1021/ct900665a

Bulk rutile TiO2 and its (110) surface have been investigated with a computationally efficient semiempirical tight binding method: self-consistent-charge density functional tight binding (SCC-DFTB). Comparisons of energetic, mechanical, and electronic properties are made to density functional theory (DFT) and to experiment to characterize the accuracy of SCC-DFTB for bulk rutile TiO2 and TiO2(110). Despite the fact that the SCC-DFTB parameters for Ti, Ti−Ti, and Ti−O were developed in the context of small biologically relevant Ti containing compounds, SCC-DFTB predicts many properties of bulk TiO2 and the TiO2(110) surface with accuracy similar to local and gradient-corrected DFT. In particular, SCC-DFTB predicts a direct band gap of TiO2 of 2.46 eV, which is in better agreement with experiment, 3.06 eV, than DFT utilizing the local density approximation (LDA), 2.0 eV. SCC-DFTB also performs similar in terms of accuracy as LDA-DFT for the phonon frequencies of the bulk lattice and for the relaxed geometry of the TiO2(110) surface. SCC-DFTB does, however, overestimate the surface energy of TiO2(110) compared to LDA-DFT. Nevertheless, the overall accuracy of SCC-DFTB, which is substantially more computationally efficient than DFT, is encouraging for bulk rutile TiO2 and TiO2(110).