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 11 surface-patterns.