Ground-state properties of rutile: electron-correlation effects

TL;DR

This paper investigates how electron-correlation effects influence the structural properties of rutile, revealing the non-linear behavior of correlation energy and its impact on lattice constants and compressibility.

Contribution

It introduces an ab-initio scheme to analyze electron-correlation effects on rutile's properties, highlighting the quadratic dependence of correlation energy on geometric deviations.

Findings

Hartree-Fock lattice constants are close to experimental values

Electronic correlations significantly renormalize compressibility

Correlation energy exhibits quadratic dependence on geometry deviations

Abstract

Electron-correlation effects on cohesive energy, lattice constant and bulk compressibility of rutile are calculated using an ab-initio scheme. A competition between the two groups of partially covalent Ti-O bonds is the reason that the correlation energy does not change linearly with deviations from the equilibrium geometry, but is dominated by quadratic terms instead. As a consequence, the Hartree-Fock lattice constants are close to the experimental ones, while the compressibility is strongly renormalized by electronic correlations.