To understand the role of chlorine in the stability and the observed fragmentation of Ag dendritic nanostructures, we have studied computationally two model systems using density functional theory. The first one relates to diffusion of Agn and AgnClm (n = 1-4) clusters on an Ag(111) surface, and the second demonstrates interaction strength of (Ag55)2 dimers with and without chloridation. Based on our calculated energy barriers, AgnClm clusters are more mobile than Agn clusters for n = 1-4. The binding energy between two Ag55 clusters is significantly reduced by surface chloridation. Bond weakening and enhanced mobility are two important mechanisms underlying corrosion and fragmentation processes. [ABSTRACT FROM AUTHOR]