Systematically Improvable Generalization of Self-Interaction Corrected Density Functional Theory

TL;DR

This paper introduces a systematic generalization of the Perdew-Zunger self-interaction correction in density functional theory, improving accuracy for both equilibrium and strongly correlated systems by bridging to wavefunction theory.

Contribution

It derives a new formalism that extends PZSIC to include correlation effects, resolving previous performance issues and enabling systematic improvements.

Findings

Minimal active spaces effectively resolve the PZSIC paradox.

The generalized method accurately handles near-equilibrium systems.

It improves treatment of strongly-correlated systems.

Abstract

Perdew-Zunger self-interaction correction (PZSIC) reintroduces an exact constraint to approximate density functional theory (DFT), but can paradoxically degrade performance and is not systematically improvable. We use the Adiabatic Projection formalism to derive PZSIC in terms of a reference system experiencing only electron self-interaction. Generalization introduces correlation into the reference system, systematically bridging from PZSIC to exact wavefunction theory. Minimal active spaces resolve the PZSIC paradox, accurately treating near-equilibrium and strongly-correlated systems.