Structural, electronic, and dynamical properties of Pca21-TiO₂ by first principles

M. Abbasnejad^1,2, M. R. Mohammadizadeh^1a and R. Maezono²

¹ Superconductivity Research Laboratory (SRL), Department of Physics, University of Tehran - North Karegar Ave., P. O. Box 14395-547, Tehran, Iran
² School of Information Science, Japan Advanced Institute of Science and Technology (JAIST) - Asahidai 1-1, Nomi, Ishikawa 923-1292, Japan

^a zadeh@ut.ac.ir

Received: 24 October 2011
Accepted: 30 January 2012

Abstract

First-principles calculations of the structural, electronic, and mechanical properties of the modified fluorite structure of TiO₂ with Pca21 symmetry are obtained using the plane-wave pseudopotential density functional theory. The results indicate that Pca21-TiO₂ is a semiconductor with an indirect band gap. The calculated static dielectric constants are larger than those of anatase and brookite, but they are much smaller than those of rutile. The calculated bulk modulus using the equation of state is in good agreement with that calculated from elastic constants. The calculated bulk modulus is in agreement with a recent theoretical and experimental report, which confirms that the experimentally claimed structure (cubic fluorite phase) can be Pca21-TiO₂.