An atomistic simulation employing the Modified Embedded Atom Method (MEAM) potential for single copper has been built in order to thoroughly investigate continuum field theory. The single crystal copper in a single slip orientation <001> is the material studied and the strain rate is limited to 108/sec in order to expose how the length size scale affect structure property for plasticity and shearing. A Fixed-end copper block undergone simple shear has been chosen to represent the model and is period in z direction while its x and y direction is set as free surfaces. The results of the molecule dynamics reveal that the size scale does affect plasticity and shearing mechanism in term of yield stress. The dislocation initiation at the edge of the computational models is the mechanical yield point occurred from. The size scale affects the plastic response as strains levels up to 20% is also achieved in simple shear for copper single slip.