Theoretical Study Of The Stable Structure And Electromagnetic Properties Of The Ti_nni_m Clusters

The structures and the properties of clusters are important issues. As many novel and unique properties both in physics and chemistry, the studies of clusters can greatly facilitate and promote the fundamental and applied research of many related subjects, such as physics, chemistry and materials. Ti-Ni alloys near equiatomic composition exhibit excellent shape memory effect that interests us, and have rich phase changes and electronic structures and good biocompatibility.Using the first principles (DMol method), we used the BLYP exchange-correlation functional and double-numerical basis with polarized functions (DNP), and we have found the ground states of the clusters. We have studied the structures and the electronic properties of binary metal Ti_nNi_m clusters. We have found the exact geometric and electronic structures by the AE calculation.The Ni_nTi (n≤7) have more low energy structures with the increasing numbers of clusters. For Ni₂Ti and Ni₃Ti, Ti atom is in the plane bridge position in the stable structures. For Ni_nTi(n=4⁷), the doped Ti atom is on the polygonal surface of the structures that Ni-atoms form. From average binding energy (Eave), the stability of Ni_nTi (n≤7) more stable than Nin (n≤7). From the second derivative of the binding energy it can be seen clearly that Ni₅Ti is the most stable structure in Ni_nTi (n≤7).We have analyzed the properties of electrons using Mulliken method. We find that Ni_nTi (n≤7) have weak magnetism. Specially, because of titanium, the magnetic moment of Ni2 and Ni3 and Ni4 vanishes.We have found the ground states of Ti_nNi_m (n, m≤4), the clusters of the ground state have no magnetic moment except Ti₂Ni and Ti4Ni.For Ti_nNi_n, it is clear that the average binding energy (Eave) monotonously descends with the increasing atom-numbers with the exceptions of Ti₅Ni₅. It means to strengthen the stability of the structures. For Ti₅Ni₅,Ti₆Ni₆, there are two low energy state structures. We have analyzed the properties of electrons of the Ti_nNi_n (n≤6) clusters using Mulliken method. For despite of the electric charges also changing the nickel atom from the titanium atom in the Ti₃Ni₃ and Ti₄Ni₄ clusters, the magnetic moment is zero. Other's magnetic moment is weak.