Supplemental Material

The electronic supplementary material includes computational results pertaining to the confor mational sampling employing the CREST, ORCA, and Molpro quantum chemical packages and the exploratory quantum chemical calculations, employing the Gaussian and Molpro quantum chemical packages. In addition, it contains overviews of previous neon matrix assignments of (H2O)m (m {less than or equal to} 5), (D2O)m (m {less than or equal to} 5), (HDO)m (m {less than or equal to} 3), (HCl)n (n {less than or equal to} 4), and (DCl)n (n {less than or equal to} 4) cluster molecules as well as experimental integrated intensities from the spot-to-spot analyses.