Eur. Phys. J. B (2017) 90: 210
https://doi.org/10.1140/epjb/e2017-80476-9

Regular Article

On the ground state of TiO₂ as predicted by all electron density functional calculations in relation to experiment

Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211-7010, USA

^a e-mail: singhdj@missouri.edu

Received: 16 August 2017
Received in final form: 31 August 2017
Published online: 7 November 2017

Abstract

The energy ordering of rutile and anatase forms of TiO₂ are reported with several density functionals as obtained using all electron calculations. Careful convergence tests were performed. Results obtained both with and without structure optimization are reported. In each case anatase is found to be more stable than rutile, in contrast to the experimental expectation. Upon full relaxation, the lattice parameters of both forms are similar to experiment regardless of the functional used. GGA functionals, which are generally regarded to be more reliable than the LDA for energies, yield a more strongly stable anatase ground state. The possibility of a poor approximation to the Ti core-electrons in pseudopotential methods can be excluded as a source of this long standing puzzle. The results are discussed in relation to experiment.