Approaching finite-temperature phase diagrams of strongly correlated materials: A case study for V2O3

Abstract

Examining phase stabilities and phase equilibria in strongly correlated materials asks for a next level in the many-body extensions to the local-density approximation (LDA) beyond mainly spectroscopic assessments. Here we put the charge self-consistent LDA+dynamical mean-field theory (DMFT) methodology based on projected local orbitals for the LDA+DMFT interface and a tailored pseudopotential framework into action in order to address such thermodynamics of realistic strongly correlated systems. Namely a case study for the electronic phase diagram of the well-known prototype Mott-phenomena system V2O3 at higher temperatures is presented. We are able to describe the first-order metal-to-insulator transitions with negative pressure and temperature from the self-consistent computation of the correlated total energy in line with experimental findings.

Free Energy from Stationary Implementation of theDFT+DMFTFunctional

“…Note also that the use of the self-consistently determined Wannier functions (which depend on self-consistent charge), as is commonly used in most of the LDA+DMFT implementations [24,29,30], leads to non-stationary LDA+DMFT solution, and non-stationary free energies.…”

“…To become material specific, DMFT was soon developed into an electronic structure tool (LDA+DMFT) [7, 8], which achieved great success in numerous correlated materials (for a review see [9]). The LDA+DMFT method has mainly been used for the calculation of spectroscopic quantities, and only a few dozens of studies managed to compute energetics of correlated solids, and only a handful of them used exact solvers and charge self-consistency [18,19,24,25,28,29]. This is not only because of the very high computational cost, but also because previous implementations of LDA+DMFT were not stationary, and hence it was hard to achieve precision of free energies needed for structure optimization and study of phase transitions in solids.…”

Calculation of metallic and insulating phases of V2O3 by hybrid density functionals

“…[16][17][18][19][20][21][22][23][24][25][26] The simple local spin density approximation (LSDA) is known to be unable to give a band gap for the insulating phases of V 2 O 3 16 due to its inability to treat the localized d electrons correctly. On the other hand, the LSDA+U method can open up a gap for open-shell d electron systems, 17 but with the disadvantage that the on-site repulsion, U, is a variable.…”

Total energy calculations using DFT+DMFT: Computing the pressure phase diagram of the rare earth nickelates

“…Fully charge selfconsistent calculations using approximate DMFT impurity solvers also have been performed to study the elastic properties of Ce [10], Ce 2 O 3 [10,11], and Pu 2 O 3 [10]. Very recently, fully charge self-consistent calculations which use continuous-time QMC to solve the DMFT impurity problem have been used to calculate the z position of the As atom in iron pnictides [12,13] and the thermodynamics of V 2 O 3 [14], Ce [15]. These most advanced studies have not yet addressed a phase transition between two different structures.…”