Advancements in Ensemble Density Functional Theory for Periodic Systems

Recent advancements in Ensemble Density Functional Theory (EDFT) have been reported in a paper titled "Approaching Periodic Systems in Ensemble Density Functional Theory via Finite One-Dimensional Models" by Remi J. Leano, Aurora Pribram-Jones, and David A. Strubbe. The authors explore the application of EDFT to periodic systems, a significant extension of its previous use in isolated systems, atoms, and molecules.

EDFT is a generalization of ground-state Density Functional Theory (GS DFT) that incorporates both ground and excited states of a system. The study specifically addresses the challenge of calculating band gaps for periodic systems, which has been a limitation in prior research. To tackle this, the authors estimate the thermodynamic limit using increasingly large finite one-dimensional systems, referred to as "particle in a box" models, that approach the uniform electron gas (UEG).

The findings indicate that corrections to the energy levels approach zero in the infinite limit, consistent with expectations for metallic systems. However, the authors also note a correction to the effective mass, which aligns with results from other calculations on one-dimensional, two-dimensional, and three-dimensional UEGs. This suggests that EDFT may yield non-trivial results for periodic systems, potentially enhancing the accuracy of energy level calculations in various materials.

This research could have implications for the development of more accurate computational methods in materials science, particularly in understanding electronic properties and behaviors in complex systems. The full paper can be accessed at arXiv:2402.17742.