  For the numerical simulations of physical and mechanical behaviors of
materials at the micro-nano scale, a coupled model with the effect of local
quantum is presented in this paper. Unlike traditional methods, the transition
region is not needed since the non-local mechanical effects and the
constitutive relations are naturally involved by first principle density
functional calculations. In order to identify and calculate the mechanical
quantities at different scales, some necessary assumptions are made when
solving Kohn-Sham equations. Basic deformation elements are introduced and
mechanical tensors are explicitly derived based on the complex Bravais lattice.
The responses of 3-demensional copper nanowires which composed of 25313 atoms
under different external loads are simulated. Strain and stress fields are
calculated and dislocation distributions are predicted during the damage
process. Numerical results confirm the validity and transferability of this
model.
