Doping induced metal-insulator phase transition in NiO

TL;DR

This paper investigates the insulator-metal phase transition in NiO using reduced density matrix functional theory and density functional theory, highlighting different mechanisms and aligning well with experimental data.

Contribution

It demonstrates that reduced density matrix functional theory provides a more accurate description of the phase transition mechanism in NiO compared to traditional density functional theory.

Findings

Spectral density from RDMFT agrees with experiments for doped and undoped NiO.

The phase transition mechanism differs: rigid shift in DFT, spectral weight redistribution in RDMFT.

Results align with experimental observations and previous many-body studies.

Abstract

The insulator to metal phase transition in NiO is studied within the framework of reduced density matrix functional theory and density functional theory. We find that the spectral density obtained using reduced density matrix functional theory is in good agreement with experiments both undoped as well as doped NiO. We find that the physical description of the hole-doping induced phase transition \emph{qualitatively differs} depending on whether NiO is calculated within density functional theory or reduced density matrix functional. In the former case the underlying mechanism of the phase transition is identified to be a rigid shift of chemical potential, while in the latter case a redistribution of the spectral weight drives the transition. These latter results are found to be in good agreement with both experiments and previous many-body calculations.