Stresses in thin films deposited on single-crystalline nanowires induce large permanent bending of the nanowires, which was previously applied to create helical structures such as nanocoils and nanoscrews by one of the authors. The bending strains reach up to a percentage of a few tens. This study was devoted to basic understanding of the bending mechanism by means of molecular dynamics simulation based on Lennard-Jones potential. Two dimensional model of a nanowire, composed of 5-atom thickness and 100-atom length, was analyzed to determine the thermodynamically stable deformation when one side of the surface was covered with a monolayer of film atoms having a misfit lattice and a different bonding energy. The results of the curvature showed significant effects of lattice misfit, rather than the bonding energy. The misfit strain of about 20% was found to meet the coherent interface. This resulted from reduction in strain energy of a film due to the bending. The relatively small curvatures observed under the non-coherent conditions and the effect of the bonding energy were explained by presence of the surface stress.
