Structural Evolution, Electronic, Bonding, and Magnetic Properties of Ti2Bn (n = 2-16) Clusters: A Computational Study.
Abstract
The structural evolution, bonding characteristics, and electronic and magnetic properties of Ti2Bn (n = 2-16) clusters have been systematically investigated. The results reveal that small clusters (n = 2-5) adopt open inverse-sandwich structures, while perfect inverse-sandwich configurations are formed at n = 6 and 7. For larger sizes, the clusters evolve into extended inverse-sandwich structures. Population analysis indicates that both Ti atoms carry positive charges, suggesting electron transfer from the Ti atoms to the boron framework. The HOMO-LUMO gaps of Ti2B6 and Ti2B7 exhibit notably large values for alpha electrons, indicating enhanced electronic stability. The average binding energies increase monotonically with cluster size, reflecting greater stability for larger clusters. Second-order energy differences identify n = 4, 7, and 12 as magic numbers. AdNDP analysis of three representative clusters, Ti2B6, Ti2B7, and Ti2B16, reveals that BB two-center two-electron σ bonds are present in Ti2B6 and Ti2B7 but absent in Ti2B16. Instead, multicenter σ and π bonds involving both Ti and B atoms are prevalent. Regarding magnetic properties, clusters with sizes n = 8, 10, 12, and 14 are nonmagnetic, while the others exhibit either ferromagnetic or antiferromagnetic behavior.