The structures of [Ag.(Ag~2S)~n=3,4) cluster were studied by using the methods of ab initio molecular orbital restrict Hartree-Fock(RHF) and density functional theory (DFT). It wasfound that the clusters with cyclic structure are most stable. The corresponding stable geometries and electronic structures were obtained. These two kinds of clusters can act as the deep trap of free electron of sulfur sensitive center.

Key words: SILVER COMPOUNDS, SULFUR COMPOUNDS, AB INITIO CALCULATION, GEOMETRICAL ISOMERISM, ELECTRONIC STRUCTURE