  We present first-principles calculations of elastic properties of
multilayered two-dimensional crystals such as graphene, h-BN and 2H-MoS2 which
shows that their Poisson's ratios along out-of-plane direction are negative,
near zero and positive, respectively, spanning all possibilities for sign of
the ratios. While the in-plane Poisson's ratios are all positive regardless of
their disparate electronic and structural properties, the characteristic
interlayer interactions as well as layer stacking structures are shown to
determine the sign of their out-of-plane ratios. Thorough investigation of
elastic properties as a function of the number of layers for each system is
also provided, highlighting their intertwined nature between elastic and
electronic properties.
