Negative Poisson's Ratio in Phagraphene

We present the results of numerical simulation of elastic properties of phagraphene, a recently predicted but not synthesized yet quasi-two-dimensional allotrope of graphene. We show that the Poisson'ss ratio is positive for the planar configuration of phagraphene and negative for the nonplanar one. Both the Poisson's ratio and the Young's modulus are isotropic for the planar phagraphene and strongly anisotropic for the nonplanar phagraphene.