Authors: Jolla Per Kullgren, Matthew Jason Wolf, Kersti Hermansson, Christof Köhler, Bálint Aradi, Thomas Frauenheim, and Peter Broqvist
Reducible oxides such as CeO2 are challanging to describe
with standard density functional theory (DFT) due to the mixed valence states of the cations, and often require the use of additional correction schemes, an
d/or more computationally expen- sive methods. This adds a new layer of complexity when it comes to the generation of Slater-Koster tables and the corresponding repulsive potentials for self-consistent density functional based tight binding (SCC-DFTB) calculations of such materials. In this work, we provide guidelines for how to set up a parameterisation scheme for mixed valence oxides within the SCC-DFTB framework, with a focus on reproducing structural and electronic properties as well as redox reaction energies calculated using a reference DFT method. This parameterisation procedure has been used to generate parameters for Ce–O interactions, with Ce in its +III or +IV formal oxidation states. The generated parameter set is validated through comparison to DFT calculations for various ceria (CeO2) and reduced ceria (CeO2−x ) systems of different dimensionalities ranging from 0D (nano-particles) to 3D (bulk). As oxygen vacancy defects in ceria are of crucial importance to many technological applications, special focus is directed towards the capability of describing such defects accurately.
J. Phys. Chem. C, 2017, 121 (8), pp 4593–4607