Negative Poisson’s ratios in few-layer orthorhombic arsenic: First-principles calculations.

Using first-principles calculations we demonstrate for the first time that few-layer orthorhombic arsenic possesses a negative Poisson’s ratio. For a single layer of arsenic, the negative Poisson’s ratio is predicted to be ∼−0.09. As the number of layers increases, the magnitude of the negative Poisson’s ratio increases and finally approaches a limit at four layers, becoming very close to the bulk value of −0.13. To understand these layer-dependent negative Poisson’s ratios, we propose a rigid mechanical model in which the intra-layer bond lengths and the normal Poisson’s ratio of the in-layer plane play key roles. [ABSTRACT FROM AUTHOR]