The structure and the thermochemical properties of the H-3(+)(H-2)(n) clusters (n=8-12)

Ab initio calculations were performed for the H-3(+)(H-2)(n) clusters (n=8- 12), including complete optimization of several isomers of the n=10 cluster . Binding energies, enthalpies, and ionization potentials are calculated. W ell defined patterns of chromism are predicted for the H-2 collective vibra tions and for the H-3(+) breathing vibrations. The calculations for the n > 10 clusters allow us to understand their shell structure in terms of conce ntric spheres of H-2 molecules. The first and second shells have occupation numbers equal to 3 and 6, respectively, while for the third shell, this nu mber is within the range 12-15. (C) 2001 American Institute of Physics.