Beyond density functional theory: the domestication of nonlocal potentials

TL;DR

This paper discusses extending density functional theory to include nonlocal potentials, proposing a new theoretical model and computational methods to improve accuracy for large molecules and solids.

Contribution

It introduces orbital functional theory (OFT) as an exact framework and proposes practical functionals and a linearized variational cellular method for implementation.

Findings

OFT is theoretically exact for N-electron systems.

New functionals are proposed for short- and long-range correlations.

LVCM simplifies implementation for molecules and solids.

Abstract

Due to efficient scaling with electron number N, density functional theory (DFT) is widely used for studies of large molecules and solids. Restriction of an exact mean-field theory to local potential functions has recently been questioned. This review summarizes motivation for extending current DFT to include nonlocal one-electron potentials, and proposes methodology for implementation of the theory. The theoretical model, orbital functional theory (OFT), is shown to be exact in principle for the general N-electron problem. In practice it must depend on a parametrized correlation energy functional. Functionals are proposed suitable for short-range Coulomb-cusp correlation and for long-range polarization response correlation. A linearized variational cellular method (LVCM) is proposed as a common formalism for molecules and solids. Implementation of nonlocal potentials is reduced to independent calculations for each inequivalent atomic cell.