Negative Poisson's ratio in monolayer PdSe2

Mechanical properties of the PdSe2 monolayer are calculated by using first-principles calculations. By adding uniaxial strain along x- and y-directions, our results show that the negative Poisson's ratio (NPR) can be observed in the Two Dimensional (2D) puckered structure of PdSe2 monolayer. The occurrence of the NPR is directly caused by the fact that the decrease of Se-Se bond is larger than the increase of Se-Pd-Se bond when compressing the lattice along the x-direction. Our calculations exhibit that the electronic locality of Se-Se bond is strong and the orbit of the Se atom in the Se-Se bond has changed significantly. Consequently, our calculated results indicate that monolayer PdSe2 will have many potential applications in nanoelectronics and microelectromechanical devices.