An ab initio study of the (H_2O)_(20)H~+and (H_2O)_(21)H~+water clusters

摘要

The study of the minimum Born–Oppenheimer structures of the protonated water clusters,(H20),,H+, is performed for n=20 and 21. The structures belonging to four basic morphologies areoptimized at the Hartree–Fock, second-order many-body perturbation theory and coupled clusterlevel, with the 6-31G, 6-31G*, and 6-311G** basis sets, using the parallel ACES III program. Thelowest energy structure for each n is found to be the cagelike form filled with H20, with the protonlocated on the surface. The cage is the distorted dodecahedron for the 21-mer case, and partiallyrearranged dodecahedral structure for the 20-mer. The results confirm that the lowest energystructure of the magic number n=21 clusters corresponds to a more stable form than that of the20-mer clusters.