DFT+U Type Strong Correlation Functional Derived from Multiconfigurational Wavefunction Theory

TL;DR

This paper introduces a new DFT+U-type functional based on multiconfigurational wavefunction theory, aimed at accurately modeling strong electron correlation effects in complex systems.

Contribution

It derives a novel functional from multiconfigurational theory that improves the treatment of strong correlation in DFT calculations.

Findings

Recovers the flat-plane condition for electron correlation.

Provides beyond-zero-sum accuracy for iron spin-crossover complexes.

Uses a block-localized configuration interaction Hamiltonian.

Abstract

We present a DFT+U-type functional for strong correlation, derived from multiconfigurational wavefunction theory. The reference system experiences electron-electron interactions only in DFT+U-type atomic states, yielding a block-localized configuration interaction Hamiltonian which depends on the atomic state occupancies and the promotion energies of doubly excited determinants. Simple approximations for the promotion energies recover the flat-plane condition and provide beyond-zero-sum accuracy for iron spin-crossover complexes.