Spectral density and metal-insulator phase transition in Mott insulators within RDMFT

TL;DR

This paper introduces a new method within reduced density matrix functional theory to calculate the spectral density of solids, accurately capturing the insulator-metal transition in MnO driven by pressure-induced crystal field splitting.

Contribution

A novel computational approach for spectral density calculation in solids within RDMFT, validated against established many-body techniques and applied to study phase transitions.

Findings

Excellent agreement with established methods for spectral density.

Pressure induces insulator-metal transition in MnO via crystal field splitting.

Charge redistribution occurs between Mn $e_g$ and $t_2g$ states during transition.

Abstract

We present a method for calculating the spectrum of periodic solids within reduced density matrix functional theory. This method is validated by a detailed comparison of the angular momentum projected spectral density with that of well established many-body techniques, in all cases finding an excellent agreement. The physics behind the pressure induced insulator-metal phase transition in MnO is investigated. The driving mechanism of this transition is identified as increased crystal field splitting with pressure, resulting in a charge redistribution between the Mn $e_g$ and $t_2g$ symmetry projected states.