Ab initio study on the kinetics and mechanisms of the formation of Agn (n=2–6) clusters

The CCSD(T)/11e-RECP//MP2/11e-RECP method was used to explore the potential energy surfaces (PESs) of the formation of Ag n ( n = 2–6) clusters. Two kinds of reaction mechanisms were revealed in the formation of Ag n clusters, the association mechanism for the formation of Ag 2 , Ag 5 , and Ag 6 clusters and the association–isomerization mechanism for the formation of Ag 3 and Ag 4 clusters. Based on the canonical transition state theory, the calculated rate constants of the formation of Ag n clusters displayed an odd–even effect: the rate constants of formation of Ag n clusters with odd number were larger than those with even number. The rate constant of formation of Ag 4 was the lowest, whereas that of Ag 5 was the highest among Ag n ( n = 2–6) clusters. The formation of Ag 4 was the most difficult step in the aggregation process of the silver clusters. The formation of Ag 4 may be related with the critical point in the silver aggregation process.