Abstract: Systematic studies on the geometry, electronic structure and vibrational properties of small (NiTi)_x clusters with x=1-3, within the framework of the density functional theory, were performed in this work.The electronic structure analyses were used to investigate the bonding between the early-late(EL) transition metals in their alloy.The results of our calculations have been used to predict (NiTi)_x clusters structure for the ground state and confirm that s-electron density is transferred from Ti atoms to Ni atoms followed by the back donation of electrons through the d-orbital.The study provides a fragment approach based on the isolobal analogy that NiTi molecular fragments play a significant role in forming clusters.

Key words: NiTi cluster, DFT, Isolobel analogy