A Stillinger-Weber Potential for Single-Layer Black Phosphorus, and the Importance of Cross-Pucker Interactions for Negative Poisson's Ratio and Edge Stress-Induced Bending

TL;DR

This paper develops a new Stillinger-Weber potential for single-layer black phosphorus, emphasizing the critical role of cross-pucker interactions in modeling its negative Poisson's ratio and edge stress-induced bending.

Contribution

It introduces a novel parameterization of the Stillinger-Weber potential that includes cross-pucker interactions, capturing unique mechanical properties of black phosphorus.

Findings

Cross-pucker interactions enable negative Poisson's ratio.

The potential accurately models edge stress-induced bending.

Cross-pucker interactions act as re-entrant hinges.

Abstract

The distinguishing structural feature of single-layer black phosphorus is its puckered structure, which leads to many novel physical properties. In this work, we first present a new parameterization of the Stillinger-Weber potential for single-layer black phosphorus. In doing so, we reveal the importance of a cross-pucker interaction term in capturing its unique mechanical properties, such as a negative Poisson's ratio. In particular, we show that the cross-pucker interaction enables the pucker to act as a re-entrant hinge, which expands in the lateral direction when it is stretched in the longitudinal direction. As a consequence, single-layer black phosphorus has a negative Poisson's ratio in the direction perpendicular to the atomic plane. As an additional demonstration of the impact of the cross-pucker interaction, we show that it is also the key factor that enables capturing of the edge stress-induced bending of single-layer black phosphorus that has been reported in ab initio calculations.