The Nature of the Interlayer Interaction in Bulk and Few-Layer Phosphorus

TL;DR

This paper uses quantum Monte Carlo calculations to investigate the interlayer forces in black phosphorus and phosphorene, revealing charge redistribution effects and challenges for density functional theory in capturing these interactions.

Contribution

It provides benchmark QMC data on interlayer interactions in black phosphorus and highlights the limitations of current vdW-corrected DFT methods.

Findings

Significant charge redistribution between layers.

Variability among vdW-corrected DFT functionals.

Failure of DFT to capture electron reorganization trends.

Abstract

An outstanding challenge of theoretical electronic structure is the description of van der Waals (vdW) interactions in molecules and solids. Renewed interest in resolving this is in part motivated by the technological promise of layered systems including graphite, transition metal dichalcogenides, and more recently, black phosphorus, in which the interlayer interaction is widely believed to be dominated by these types of forces. We report a series of quantum Monte Carlo (QMC) calculations for bulk black phosphorus and related few-layer phosphorene, which elucidate the nature of the forces that bind these systems and provide benchmark data for the energetics of these systems. We find a significant charge redistribution due to the interaction between electrons on adjacent layers. Comparison to density functional theory (DFT) calculations indicate not only wide variability even among different vdW corrected functionals, but the failure of these functionals to capture the trend of reorganization predicted by QMC. The delicate interplay of steric and dispersive forces between layers indicate that few-layer phosphorene presents an unexpected challenge for the development of vdW corrected DFT.