A SYMMETRICAL STRUCTURE OF THE GAS-PHASE H-3(-2)(9) CLUSTER()(H)

Structures of the gas-phase clusters, H-3(+)(H-2)(n) (n = 0-10) and bi nding energies of H-3(+)(H-2)(n) and D-3(+)(D-2)(n) (n = 1-9) were cal culated with a modified G2 theory, called G2 here. Theoretical bindin g energies and their isotope effects are in good agreement with experi mental data. Shell structures were examined carefully. The n = 7 clust er is the second half-shell where one H-2 molecule above the H-3(+)(H- 2)(3) first solvation shell and three below the shell. The H-3(+)(H-2) (9) cluster is the complete second shell. The C-3-symmetry condition i s required to form shells. Therefore, the 'magic number' n = 6 is not effective in the H-3(+)(H-2)(n) cluster. (C) 1998 Elsevier Science B.V . All rights reserved.