Surface structures and thermodynamics of low-index of rutile, brookite and anatase – A comparative DFT study

Titania surfaces have been studied theoretically and experimentally for many decades due to their photocatalytic properties. In this paper we present a theoretical study where we compare the low-index surfaces of rutile, anatase and brookite in terms of their stability and relaxation. The convergence behavior with the number of layers is analyzed with large all-electron basis sets and a hybrid DFT method (PW1PW). With this method a good agreement with recent experimental results for the surface relaxation is achieved. Frequency calculations for all considered surfaces were performed to obtain surface enthalpies and analyze the stability of the 1 × 1 surface-patterns.