We have used density functional theory (DFT) implemented in the Spanish initiative for electronic simulations with thousands of atoms (SIESTA) . The norm-conserving pseudopotentials in the semilocal form are used . The generalized gradient approximation (GGA) functional with Perdew-Burke-Ernzerhof(PBE) is adopted to treat underlying exchange and correlation within the double zeta plus polarization (DZP) basis sets. Brillouin zone integration has been performed using 15×15×1 Monkhrost pack scheme. An energy cutoff of 350 Rydberg is used for the expansion of the reciprocal space. The atomic relaxation was achieved when the force reached the value of 0.02 eV/Å using the standard conjugate-gradient (CG) technique. The convergence criteria for the energy of the self-consistent field is set to be 1.0 × 10 -6 eV. The vacuum gap of 25 Å is set along the z-direction to prevent unwanted interactions between the adjacent unit cells. The chemical stability is ensured by calculating and analyzing the formation ( ) and cohesive ( ℎ ) energies.