Competition between monomer and dimer fragmentation pathways of cationic CuN clusters of N=2-20

Density functional theory calculations are performed to study the structural evolution of cationic copper clusters of N = 2-20 size range. The first shape transition occurs at N = 4, from planar to three dimensional, while the second at N = 16, from layered to capped icosahedra. Distinct even-odd alternation and closing-shell effects in binding energy are noted when size varies. Two fragmentation pathways for each cation are investigated and compared to available experiments. The competition between the two pathways is rationalized from respective dissociation energies which are size and structure dependent.