Exchange and correlation energy functionals for two-dimensional open-shell systems

TL;DR

This paper develops new exchange and correlation energy functionals for two-dimensional open-shell systems, explicitly including current and spin effects, and demonstrates their superior performance over standard approximations.

Contribution

The authors introduce novel functionals based on exact constraints and proportionality assumptions, improving accuracy for 2D systems with currents and spin polarization.

Findings

Outperform standard local spin-density approximation in finite systems

Perform well in the homogeneous 2D electron gas limit

Explicitly incorporate current and spin effects

Abstract

We consider density functionals for exchange and correlation energies in two-dimensional systems. The functionals are constructed by making use of exact constraints for the angular averages of the corresponding exchange and correlation holes, respectively, and assuming proportionality between their characteristic sizes. The electron current and spin are explicitly taken into account, so that the resulting functionals are suitable to deal with systems exhibiting orbital currents and/or spin polarization. Our numerical results show that in finite systems the proposed functionals outperform the standard two-dimensional local spin-density approximation, still performing well also in the important limit of the homogeneous two-dimensional electron gas.