Mechanical properties and total energy of SiNWs were studied based on first principle method via density functional theory. Abinit code were used for calculation as implemented in Linux coupled with Matlab scripts. Effect of various sizes and orientations on mechanical properties and total energy of silicon nanowire were identified. The mechanical properties and total energy at (001), (110) and (111) were determined. The atomic interaction in the wires influenced various mechanical parameters of the wire. The results show the strain for the three orientations were 0.1164×10-5, 0.12×10-5 and 0.115×10-5 with modulus of 149.6GPa, 75.5GPa and 85.1GPa respectively.
