First Principle Description of Correlated Transition-Metal Oxides

The general theme of this work is the investigation of strongly correlated materials via a first-principles approach. Tackling such complex systems in this fashion is relatively unusual, and notoriously difficult. We em- ploy the pseudo self-interaction correction local density functional method, PSIC, which removes the spurious self-interaction repulsion present in local or semilocal density functionals (LDA, GGA). PSIC appears to pull off a considerably better performance than local DFT methods in describing correlated materials at the realistic level typical of ab initio methods. It enables us to take on an array of fairly sophisticated problems in a variety of difficult materials unapproachable by semilocal functionals. Those treated in this work include quantum oscillation in underdoped cuprates, the magnetic structure and stability of rocksalt like cupric oxide, the electronic, structural, and magnetic properties of the correlated perovskites YTiO3 and LaTiO3 , the magnetic properties of MnO and NiO under hydrostatic pressure, charge disproportionation in complex oxides, and phase transitions to a low-temperature exotic phase of layered nickel oxide. The work provides important insights on these problems, but more generally it further validates PSIC as a new useful viewpoint on many puzzles in the area of complex correlated materials.