Poisson's ratio and Young's modulus in single-crystal copper nanorods under uniaxial tensile loading by molecular dynamics

The single crystal copper nanorods, of different cross section sizes and with crystallographic orientations [1 0 0] [1 1 0] and [1 1 1] along their length directions are simulated using molecular dynamics method. Some mechanical concepts of molecular dynamics simulation, that are nature strain, modified Poisson's ratio and modified Young's modulus, are defined. The nature strain shows the yielding and necking of material, which is different from the traditional strain. [1 0 0] nanorods show structure symmetry, whose Poisson's ratio and Young's modulus are about five times those of macroscopic scale. Also, with cross section size increasing the stable value of Poisson's ratio decreases but Young's modulus is almost invariable. For the other orientation nanorods Poisson's ratio has two stable values in the cross section directions and Young's modulus only have the maximum value rather than stable value.