Linear-scaling DFT+U with full local orbital optimization

TL;DR

This paper introduces a linear-scaling DFT+U approach using local orbital optimization and nonorthogonal projectors, enabling efficient calculations for large systems like nickel oxide nano-clusters with thousands of atoms.

Contribution

It develops a novel linear-scaling DFT+U method with full local orbital optimization and nonorthogonal projectors, improving efficiency and convergence for large systems.

Findings

Achieved linear scaling for systems over 7,000 atoms

Demonstrated systematic variational convergence

Applied successfully to nickel oxide nano-clusters

Abstract

We present an approach to the DFT+U method (Density Functional Theory + Hubbard model) within which the computational effort for calculation of ground state energies and forces scales linearly with system size. We employ a formulation of the Hubbard model using nonorthogonal projector functions to define the localized subspaces, and apply it to a local-orbital DFT method including in situ orbital optimization. The resulting approach thus combines linear-scaling and systematic variational convergence. We demonstrate the scaling of the method by applying it to nickel oxide nano-clusters with sizes exceeding 7,000 atoms.