Lowest-energy structures of AlnPn (n = 1–9) clusters from density functional theory

The lowest-energy structures of AlnPn clusters up to n = 9 have been explored using all-electron density functional calculations with a gradient correction. For smaller AlnPn clusters with n = 1–4, we successfully reproduced the previously reported lowest-energy structures. Novel cage structures with Al–P alternating arrangement were observed for n ⩾ 5. The comparison of the lowest-energy structures of AlnPn clusters with those of Si2n, BnNn, and GanAsn clusters has been made. Size-dependent cluster properties such as binding energy, HOMO–LUMO gaps, electron affinities, and photoelectron spectra have been computed and compared with experiments.