This Letter uses density functional, dynamical mean field, and Landau-theory methods to elucidate the interplay of electronic and structural energetics in the Mott metal-insulator transition. A Landau-theory free energy is presented that incorporates the electronic energetics, the coupling of the electronic state to local distortions and the coupling of local distortions to long-wavelength strains. The theory is applied to Ca2RuO4. The change in lattice energy across the metal-insulator transition is comparable to the change in electronic energy. Important consequences are a strongly first order transition, a sensitive dependence of the phase boundary on pressure and that the geometrical constraints on in-plane lattice parameter associated with epitaxial growth on a substrate typically change the lattice energetics enough to eliminate the metal-insulator transition entirely.
@article{arxiv.1801.06215,
title = {Lattice Energetics and Correlation-Driven Metal-Insulator Transitions: The Case of Ca$_2$RuO$_4$},
author = {Qiang Han and Andrew Millis},
journal= {arXiv preprint arXiv:1801.06215},
year = {2018}
}