Metallic nanowires are known to have large potential for applications in NEMS/MEMS. The high surface area to volume ratio and low defect density provide the nanowires with superior mechanical properties. Therefore, it becomes necessary to characterize the deformation behaviour of nanowires. With rapid progress of computational capability and the availability of reliable inter-atomic potentials, molecular dynamics (MD) has become an important simulation tool to examine the deformation behaviour at nanoscale.  The deformation behaviour of the metallic nanowires generally depends on crystal orientation, size, aspect ratio, type of loading (i.e., tension or, compression), temperature, and strain rate. In the present investigation, MD simulations have been performed on the tensile deformation of <100>/{100} FCC Cu nanowires with aspect ratio ranging from 0.5 to 30. The aspect ratio has been varied in two different ways. In one case, the aspect ratio is varied by changing the nanowire cross section width from 43.4 to 0.72 nm for constant length of 21.7 nm and in other case; it is varied by changing the nanowire length from 3.61 nm to 216.9 nm for constant cross section width of 7.23 nm. 

It has been found that irrespective of aspect ratio, yielding and plastic deformation is dominated by slip of partial dislocations and associated twinning mechanism. All the nanowires fail in ductile manner irrespective of aspect ratio. In the case of varying the aspect ratio by changing the nanowire cross section width at constant length, the variations in ductility can be attributed to defect nucleation sites and large amount of pre- and post-necking deformation. Further, in nanowires with high aspect ratios, formation of pentagonal atomic chains has been observed in the necking region 

Furthering the previous study, the deformation of perfect nanowires under the influence of various parameters such as orientation, shape, size, strain rate, temperature and mode of loading  has been investigated.