STRUCTURES AND STABILITY OF HYDRATED CLUSTERS OF HYDROGEN-CHLORIDE, HCL(H2O)(N), N=1-5

The molecular structures of the hydrated clusters of the HCl molecule, HCl(H2O)(n), n=1-5, are examined by employing density functional mole cular orbital methods. The most stable structures of the n=1-3 cluster s are found to be of;the proton nontransferred type. In the case of th e n=4 cluster, the proton nontransferred and proton transferred struct ures have nearly similar energies. There are several stable isomers fo r the n=5 case and the structures of these isomers are found to be all proton transferred. The relative stabilities of the direct ion-pair H +Cl- (H2O)(n) and the indirect ion-pair H3O+(H2O)(n-1)Cl- are discusse d in conjunction with their structures. The prediction of the IR spect ra of the stable HCl(H2O)(n) clusters clearly indicate the large red-s hifts of the H-Cl stretching and hydrogen-bonded O-H stretching freque ncies. (C) 1998 American Institute of Physics.