A density functional theory study on the Ag n H (n=1-10) clusters

Density functional GGA-PW91 method with DNP basis set is applied to optimize the geometries of Ag (n) H (n = 1-10) clusters. For the lowest energy geometries of Ag (n) H (n = 1-10) clusters, the hydrogen atom prefers to occupy the two-fold coordination bridge site except the occupation of single-fold coordination site in AgH cluster. After adsorption of hydrogen atom, most Ag (n) structures are slightly perturbed and only the Ag-6 structure in Ag6H cluster is distorted obviously. The Ag-Ag bond is strengthened and the strength of Ag-H bond exhibits a clear odd-even oscillation like the strength of Au-H bond in Au (n) H clusters, indicating that the hydrogen atom is more favorable to be adsorbed by odd-numbered pure silver clusters. The adsorption strength of small silver cluster toward H atom is obviously weaker than that of small gold cluster toward H atom due to the strong scalar relativistic effect in small gold cluster. The pronounced odd-even alternation of the magnetic moments is observed in Ag (n) H systems, indicating that the Ag (n) H clusters possess tunable magnetic properties by adsorbing hydrogen atom onto odd-numbered or even-numbered small silver cluster.