Self-interaction corrected electronic structure of Ti4O7, TiO2 and Ti2O3

Titanium oxides have a range of applications in, e.g., catalysis and resistive switching. There are many oxide structures with different ground states and electronic properties that have to be understood for potential applications to be possible. We have studied rutile TiO$_{2}$, Ti$_{2}$O$_{3}$, and Magn\'eli phase Ti$_{4}$O$_{7}$ using density functional theory with self-interaction corrections to account for electronic correlations, which are important in these structures. The ground state of the low temperature (LT) phase of Ti$_{4}$O$_{7}$ is found to be a new semiconducting state with antiferromagnetic coupling between two sublattices. Depending on the charge screening strength, different Ti-O phases are best described by applying different values of an empirical parameter $\alpha $, which represents the magnitude of the applied self-interaction correction. We will show that Pauli paramagnetism of the metallic high-temperature Ti$_{4}$O$_{7}$ phase is predicted using $\alpha \approx $0, that the band gaps of small-gap LT-Ti$_{4}$O$_{7}$ and Ti$_{2}$O$_{3}$ are captured by $\alpha \approx $0, while the large band gap of TiO$_{2}$ is reproduced using $\alpha \approx $0.9. Nevertheless, restricting $\alpha $ to the standard value of 0.5 for transition metal oxides is found to be a good compromise describing reasonably well the electronic structures of all these oxides. We gratefully acknowledge the computing resources provided on Blues, a high-performance computing cluster operated by the Laboratory Computing Resource Center at Argonne National Laboratory. Argonne National Laboratory's work was supported under U.S. Department of Energy contract DE-AC02-06CH11357.