THEORETICAL-STUDIES OF THE CLATHRATE STRUCTURES OF (H2O)(20), H+(H2O)(20) AND H+(H2O)(21)

Structures of (H2O)(20) (W20), H+ (H2O)(20) (HW20) and H+ (H2O)(21), (HW21) clusters were determined by applying the Zerner's intermediate neglect of differential overlap self-consistent field unrestricted Hartree-Fock (ZINDO SCF UHF) method after appropriate parametrization and yield a dodecahedral arrangement (distorted) of twenty oxygen atoms in each case. In HW21 cluster a water molecule is enclosed within the cavity of a HW20 cage structure with a stabilization energy (SE) of around 302 kcal/mol (relative to separated constituent molecules) and the most stable W20 and HW20 clusters have SE values of around 182 and 293 kcal/mol. Our results compare quite well with reported experimental observations on these clusters.