First, the fcc gold bulk (3D) structure is optimized by using the conjugate gradient (CG) approximation integrated into the SIESTA code. The optimized value of the lattice constant for the fcc 3D counterpart of the nanowire is found to be 4.10 Å which is very close to the experimental measures. This ensures the accuracy of the pseudopotential. A unit cell consisting of four gold atoms is used for the electronic and mechanical properties calculation of AuNW. The optimized bond distance between gold atoms in the linear chain is 2.51 Å. Further, the cohesive energy of the nanowire is calculated by subtracting the energy of the isolated atom from the total energy of the system. The cohesive energy of the AuNW is -1.52 eV/atom. Furthermore, the cohesive energy and the nature of the chemical bond are closely correlated. The nature of the bond is observed by the Mulliken charge density analysis (FIG. ). There is a small distortion of the overlapped wave function at the center of Au atoms. That indicates that the gold atom possesses a partly ionic and partly covalent bond. These results are in good agreement with previous studies . Further, to get insight into the electronic properties of the nanowire, we execute the spin-independent electronic properties calculation. The band structure (FIG. )) shows that one band crosses the Fermi level that indicates the linear AuNW is purely metallic. According to the Landauer formulation, the amount of band which is crossing over the Fermi level represents the amount of quantum conductance or the number of conduction channel 'G 0 ' in units of G 0 = 2e 2 h With this expression, the quantum conductance can be evaluated from the electronic band structures. The quantum conductance G 0 is associated with each state which is crossing over the Fermi level. Therefore, overall quantum conductance is given by nG 0 , where, n indicates the number of channels crossing over the Fermi level. Since only one band is crossing the Fermi level, the quantum conductance is found to be 1G 0 . Additionally, there are a large number of flat bands around the energy range in -0.5 eV and some flat band appears around -2.1 eV of the valence bands. These flat bands give rise to a variety of exotic manybody phenomena. This result is in very good agreement with the previous studies . Further, the calculated projected density of states FIG. ) depicts that the 5d orbital is mainly contributing in the valence band region and conduction band minimum region closer to the Fermi level. But the contribution is dominated by the 6s orbital in the higher energy region of the conduction band. It's worth mentioning that a similar orbital contribution is found fcc bulk counterpart .