Ab initio studies on (H ₂O) ₁₄ ^- clusters: Existence of surface and interior-bound extra electrons

A recent paper by Turi et al. [Science 309, 914 (2005)] suggests that the anionic water clusters smaller than (H ₂O) ₄₅ ^- (at a low temperature) will only have surface-bound extra electrons and no internally bound electrons. Accordingly, (H ₂O) ₁₄ ^- cluster isomers should only have surface-bound extra electrons. The ab initio results presented here, however, suggest that the (H ₂O) ^14- cluster isomers can have two distinct types of isomers with almost the same energy. The one type of isomer (type 1) has all the non-H-bonding H atoms (NHB H) directed outward and surface-bound extra electron while the other type (type 2) has a number of NHB H atoms directed toward cavity and has an interior-bound electron, and thus, contradicts the earlier quantum simulation results of Turi et al.