Structure and electronic properties of medium-sized GanNn clusters (n = 4–12)

The lowest-energy structures were obtained for GanNn clusters (n = 4–12) using gradient-corrected density functional theory. For each cluster size, a number of structural isomers were constructed and optimized. Crossover from ring to cage-like structures were found at Ga8N8. The observed cage-like configurations consisting of six-membered rings with gallium–nitrogen alternative arrangement can be viewed as embryo of wurtzite structure of gallium nitride crystal. The size-dependence of cluster properties such as binding energy, HOMO–LUMO gaps, ionization potentials, electron affinities, and Mulliken charges have been computed and analyzed. The bonding characteristics of the GanNn clusters were discussed.