THE STRUCTURE AND STABILITY OF CLN- CLUSTERS, N=2-7

The electronic and geometrical structure of the ground and some low-lying states of the Cl(n)- species, n = 2-7, and corresponding neutrals are calculated within the local density functional approximation with inclusion of the nonlocal Becke corrections in the total energy calculations. The vertical electron affinity (EA), the adiabatic EA for neutrals and the first ionization potential (FIP) of anions are obtained. It is shown that the adiabatic corrections are relatively small in all cases. According to the results of calculations all anions have a ground state which is stable with respect to both electron detachment and dissociation through the lowest energy channel, and some of them have a second (excited) stable state as well. On the contrary, Cl4 and Cl5 appear to be weakly stable and Cl6 is unstable toward dissociation to Cl2 and the rest of the neutral. Despite the antibonding character of the highest molecular orbital of a neutral which accepts an additional electron, the EA of all species is quite high and it is maximal for Cl7. In the latter case the adiabatic EA value attains 5.4 eV. The interesting feature of both neutrals and anions consists in their trend to fragmentation in Cl2 and Cl3 units.