Using the SO(2, 1) radial (or spectrum-generating) subgroup of the SO(4,2) dynamical group of the Coulomb problem, we construct the associated coherent states that follow the classical radial motion. These wave packets evolve in a 6ctitious time variable proportional to the eccentric anomaly. The packets consist of a superposition of Coulomb Sturmian functions and do not disperse as they evolve although the width of the packets changes periodically.

Effective pair potential functions are used to study the adsorption of a water molecule on surfaces of β-AgI. The water molecule is represented by a rigid point charge ST-2 model and the AgI substrate by an array of point atoms with effective charge ±0.6e, Lennard-Jones cores, and ionic polarizabilities. Maximal binding energy surfaces and optimal H2O configurations are generated for the water molecule adsorbed on the rigid and unrelaxed basal and prism AgI faces. Adsorption of the H2O above a two layer ledge, an iodine vacancy, and an H2O trapped in the vacancy are modeled for the iodine basal face and compared with results for the smooth substrates. These studies indicate the H2O adsorption is favored at ’’interstitial’’ sites where no substrate atoms lie directly below either in the first or second layer. The prism face is found to attract the water molecule more strongly and provide larger energy barriers to surface diffusion. The model predicts maximal binding energies of 20 and 16 kcal/mole for the adsorbed H2O on the preferred prism and basal face sites, respectively. The iodine vacancy produces an adsorption site with optimal binding energy 19 kcal/mole and the two layer ledge results in an extended region of strong binding sites of order 20 kcal/mole. The water molecule trapped in the I vacancy creates a surface charge ’’defect’’ around which additional water molecules could cluster with dipole moments in configurations favorable for H2O–H2O bonding.

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A previous study of the water monomer on the basal faces of ice is extended to consider the interaction of the water molecule with a rigid prism face of ice and with an ice basal face ledge. The effective central force H2O–H2O potentials of Stillinger and Rahman are used to generate maximal binding energy surfaces for the H2O adsorbed on the sample substrates. The results indicate that the prism face of ice binds the water molecule more strongly than the basal faces, and the step on the basal face serves to expose high binding sites on the prism face and multiple bonding configurations at the base of the ledge. Bonding on all the substrates is preferred at sites not directly above water molecules in the first or second layer. Average maximal binding energies on the prism and ledge surfaces are 9 kcal/mol compared to a value of 8 kcal/mol on the (unpolarized) basal face. Optimal bonding configuration for the adsorbed water moment are also presented. Barriers to diffusion between maximal binding sites are 2.5 and 3.0 kcal/mol on the basal and prism faces, respectively.