Using DFT to investigate Ca₂MoO₄ as a potential MIT candidate

Metal-insulator transition (MIT) materials have occurred in families of chemically adjacent structures, such as members of the rare earth nickelates. So, it follows that searching in the composition space around known MITs is a promising avenue of identifying new ones. The MIT Ca₂RuO₄, which has a Ruddlesden-Popper (RP) structure, has been shown to involve an interplay between Mott physics and a Jahn-Teller distortion. A chemically similar RP neighbor is Ca₂MoO₄ as Mo⁴⁺ with a d² electronic configuration is a hole analogue to Ca₂RuO₄. With density functional theory, we predict that the ground state structure of the molybdate shares the Pbca space group with Ca₂RuO₄. We then explore how electron correlation, structural distortion, and magnetism contribute to the MIT mechanism, then conclude with comparisons to the transition mechanism in Ca₂RuO₄.