First principles study of small palladium cluster growth and isomerization

Structures and physical properties of small palladium clusters Pd _n up to n = 15 and several selected larger clusters were studied using density functional theory under the generalized gradient approximation. It was found that small Pd_n clusters begin to grow 3-dimensionally at n = 4 and evolve into symmetric geometric configurations, such as icosahedral and fcc-like, near n = 15. Several isomers with nearly degenerate average binding energies were found to coexist and the physical properties of these clusters were calculated. For several selected isomers, relatively moderate energy barriers for structural interchange for a given cluster size were found, implying that isomerization could readily occur under ambient conditions.