We investigate the mechanical strength of the nanowire by applying a uniaxial strain. The 1D ultrathin system is insufficient to find the tensile stiffness (C) in order to estimate the mechanical strength. We have followed the methodology of reference . We have calculated the tensile stiffness of the nanowire by varying the lattice parameters within the range of -2% to +2% at the step of 0.5% . The tensile stiffness is the most basic mechanical properties which are defined by