Theoretical study of triatomic silver (Ag3) and its ions with coupled-cluster methods and correlation-consistent...

Coupled-cluster calculations including non-iterative effects of triple excitations (CCSD(T)) have been made with correlation-consistent basis sets to study a range of properties of Ag3, Ag3(-), and Ag3(+). The methodology was tested on atomic and diatomic silver systems. The accuracy achieved for these systems suggests that predictive-quality results can be expected for the triatomic systems. Properties of the triatomic systems studied include structures and energies of ground and excited states (bent and linear geometries), dissociation energies, ionization energies, and vertical electron detachment energies. In the absence of experimental structural data, the present calculated data serve as reliable predictions. The calculated dissociation energies are near the middle of the experimental range (253 ± 13 kJ mol(-1)). The calculated ionization energies clearly favor the lower of the two experimental measurements (i.e. 5.66 eV). Our calculated vertical electron detachment energies of linear Ag3(-) match the observed photoelectron data fairly well. Overall the higher levels of theory used in the present study achieve consistent accuracy for a range of properties. In contrast, some prior density-functional theory studies provide good results for certain properties, but are lacking in accuracy for others. Another feature of the present study is that it has not been necessary to empirically correct results on the triatomic systems because of known deficiencies in the results on atomic and diatomic systems. The majority of prior wave function-based studies cannot make this claim.