Electronic delocalization in small water rings.

Water clusters are known to form through hydrogen bonding. However, this study shows that the formation of small water clusters such as (H2O)n with n = 3 or 4 involves strong electron delocalization. Our first-principles calculations reveal that the electron delocalization originates from both the H and O atomic orbitals and extends to the ring center, enriching the bonding characteristics of water clusters.