Theoretical study on the structure and stability of hydrogen-ion clusters Hn and Hn (n = 3, 5, 7, 9, 11, 13)

Ab initio SCF and CI calculations have been carried out for H_n⁺ and H_n⁻ (n = 3, 5, 7, 9, 11, 13) clusters with a double-zeta plus polarization basis set. The stabilization energy of negative ion clusters H_n⁻ is very small (less than 1 kcal) and their existence is critical. The structural difference between positive- and negative-ion clusters are discussed in terms of the bonding ability involved. While H_n⁺ is a charge-transfer complex, the stability of H_n⁻ comes mainly from the ion-induced-dipole attractions. The electron correlation effect on the structure and stability of these ion clusters is also discussed.