Structural disassembly, dangling bond and hydrogen storage of NinSn (n=2-10) clusters

Computational cluster sciences are rooted in geometrical optimization successes of small groups of atoms or molecules. Following size growth and element increases, optimizations are arduous and hardly generalized in certain patterns, despite advances in calculation algorithm and computing powers. Herein, a disassembly-assembly strategy is introduced to reach stable structures of binary Ni _n S _n ( n = 2-10) clusters. The lowest-energy Ni _n S _n isomers can be viewed as nestifications of low-lying Ni _n and S _n components. Identical spatial orientations in and out of the Ni-S binary systems are kept for the elemental S _n and Ni _n clusters. At the same corresponding number n , the metal and chalcogenide clusters coincidentally possess the same point group and such a trend is kept up to the NiS crystalline phase. As a result, the growth pattern of the compound clusters is simply viewed as an assembly process of their component clusters. Furthermore, molecular orbital analysis indicates that the nested structures are endowed with a large amount of dangling bonds to adsorb hydrogen atoms for hydrogen storage. Such an assembly-disassembly route in structural optimizations is hoped to serve as a route map in future functional cluster predictions.