based on harmonic frequency calculations. Although these cyclic clusters all have multiple O‐H vibrational bands, the most intense ones for each cluster size (the ring stretches) are close in frequency and thus merge into a single band, which is particularly intense. Indeed, ab initio calculations show that the intensities of the O‐H modes associated with less symmetric structures, in which the molecules are inequivalent, are much smaller than for the cyclic structures (26). Analogous effects were observed in the case of the linear chains of HCN (27), where the most redshifted C‐H stretches have the highest intensity. The application of a large electric field has no influence on this band, which further supports the cyclic structure. In contrast with the polar chains of HCN reported previously (28), for which an electric field markedly sharpens and intensifies the spectrum, the equilibrium geometry for the cyclic water hexamer is nonpolar and no such effect is expected. The cyclic tetramer is also nonpolar, and although the cy