Poisson's ratio of two-dimensional hexagonal crystals: A mechanics model study

The Poisson's ratio of two-dimensional hexagonal crystals has been widely studied due to its fundamental and fantastic nature. However, the issue involved in the regulation strategy and in the bounds of Poisson's ratio of two-dimensional hexagonal crystals has not been addressed. In this work, we predict that the Poisson's ratio of two-dimensional hexagonal crystals can be controlled by modifying the structural interaction therein, where the lower bound and upper bound are −1∕3 and +1, respectively. Furthermore, molecular simulations verify these predictions. Finally, the underlying mechanism is revealed as the interplay between two deformation modes (i.e., bond stretching and angle changing). This work provides an universal regulation strategy to tune the Poisson's ratio of two-dimensional hexagonal crystals, and determines fundamental limits on the Poisson's ratio of two-dimensional hexagonal crystals.