A functional of the one-body-reduced density matrix derived from the homogeneous electron gas: Performance for finite systems

TL;DR

This paper extends a density-matrix functional derived from the homogeneous electron gas to finite molecular systems, demonstrating its strong performance in predicting energies at equilibrium and dissociation limits.

Contribution

It introduces a method to adapt a uniform electron gas-based functional for finite systems, showing its effectiveness across various molecules.

Findings

Functional performs well at equilibrium geometries.

Functional accurately predicts dissociation energies.

Extension from uniform gas to finite systems is successful.

Abstract

An approximation for the exchange-correlation energy of reduced-density-matrix-functional theory was recently derived from a study of the homogeneous electron gas (N.N. Lathiotakis, N. Helbig, E.K.U. Gross, Phys. Rev. B 75, 195120 (2007)). In the present work, we show how this approximation can be extended appropriately to finite systems, where the Wigner Seitz radius r_s, the parameter characterizing the constant density of the electron gas, needs to be replaced. We apply the functional to a variety of molecules at their equilibrium geometry, and also discuss its performance at the dissociation limit. We demonstrate that, although originally derived from the uniform gas, the approximation performs remarkably well for finite systems.