Photoemission spectrum in paramagnetic FeO under pressure: towards an \textit{ab-initio} description

Abstract

In this work we provide an exhaustive study of the photemission spectrum of paramagnetic FeO under pressure using a refined version of our recently derived many-body effective energy theory (MEET). We show that, within a nonmagnetic description of the paramagnetic phase, the MEET gives an overall good description of the photoemission spectrum at ambient pressure as well as the changes it undergoes by increasing pressure. In particular at ambient pressure the band gap opens between the mixed Fe $t_{2g}$ and O $2p$ states and the Fe 4s states and, moreover, a $d$-$d$ gap opens, which is compatible with a high-spin configuration (hence nonzero local magnetic moments as observed in experiment), whereas decreasing pressure the band gap tends to close, $t_{2g}$ states tend to become fully occupied and $e_g$ fully unoccupied, which is compatible with a low-spin configuration (hence a collapse of the magnetic moments as observed in experiment). This is a remarkable result, since, within a nonmagnetic description of the paramagnetic phase, the MEET is capable to correctly describe the photoemission spectrum and the spin configuration at ambient as well as high pressure. For comparison we report the band gap values obtained using density-functional theory with a hybrid functional containing screened exchange (HSE06) and a variant of the $GW$ method (self-consistent COHSEX), which are reliable for the description of the antiferromagnetic phase. Both methods open a gap at ambient pressure, although, by construction, they give a low-spin configuration; increasing pressure they correctly describes the band gap closing. We also report the photoemission spectrum of the metallic phase obtained with one-shot fully-dynamical $GW$ on top of LDA, which gives a spectrum very similar to DMFT results from literature.

8 pages, 6 figures

References in corpus (15)

• Optimized norm-conserving Vanderbilt pseudopotentials
• The PseudoDojo: Training and grading a 85 element optimized norm-conserving pseudopotential table
• All-electron self-consistent GW approximation: Application to Si, MnO, and NiO
• Implementation of an all-electron GW approximation based on the PAW method without plasmon pole approximation: application to Si, SiC, AlAs, InAs, NaH and KH
• Reduced Density Matrix Functional for Many-Electron Systems
• A polymorphous band structure model of gapping in the anti-ferromagnetic and paramagnetic phases of the Mott insulators MnO, FeO, CoO, and NiO
• Experimental and theoretical evidence for pressure-induced metallization in FeO with the rock-salt type structure
• Density-Matrix-Power Functional: Performance for Finite Systems and the Homogeneous Electron Gas
• Spectral density and metal-insulator phase transition in Mott insulators within RDMFT
• Performance of one-body reduced density matrix functionals for the homogeneous electron gas
• Magnetic Collapse and the Behavior of Transition Metal Oxides at High Pressure
• Orbital Selective Pressure-Driven Metal-Insulator Transition in FeO from Dynamical Mean-Field Theory
• Metal-insulator transition and local-moment collapse in FeO under pressure
• Photoemission Spectra from Reduced Density Matrices: the Band Gap in Strongly Correlated Systems
• Convergence of quasiparticle self-consistent GW calculations of transition metal monoxides

Cited by in corpus (2)

• Introducing screening in one-body density matrix functionals: impact on the Extended Koopmans' Theorem's charged excitations of model systems
• Screened extended Koopmans' theorem: photoemission at weak and strong correlation