  Most recently, a brand new phosphorus allotrope called green phosphorus has
been predicted, which has a direct band gap up to 2.4 eV, and its single-layer
form termed green phosphorene shows high stability. Here the mechanical
properties and the uniaxial strain effect on the electronic band structure of
green phosphorene along two perpendicular in-plane directions are investigated.
Remarkably, we find that this material can sustain a tensile strain in the
armchair direction up to a threshold of 35\% which is larger than that of black
phosphorene, suggesting that green phosphorene is more puckered. Our
calculations also show the Young's modulus and Poisson's ratio in the zigzag
direction are four times larger than those in the armchair direction, which
confirm the anisotropy of the material. Furthermore, the uniaxial strain can
trigger the direct-indirect band gap transition for green phosphorene and the
critical strains for the band gap transition are revealed.
