THEORETICAL INVESTIGATION OF WEAKLY-BOUND COMPLEXES OF B WITH H-2

Continuing an earlier study [M. H. Alexander, J. Chem. Phys. 99, 6014 (1993)] of the B(P-2)... H-2 complex, we report here a further investi gation into the adiabatic-->diabatic transformation for this system, c haracterized by three potential energy surfaces (PES's) which become a symptotically degenerate. The diabatic PES's are used to determine the energies of the lowest bend-stretch levels of complexes of B(P-2) wit h either o- or pH(2). The predicted dissociation energies (D-0) are 27 .9 and 38.6 cm(-1) for the complexes with pH(2) and oH(2), respectivel y, and 37.3 and 48.5 cm for the complexes with oD(2) and pD(2), respec tively. The motion of the oH(2) moiety within the cluster cannot be de scribed accurately using a single electronic potential energy surface. In addition, new ab initio calculations are reported for the complex of H-2 With B in its first electronic excited state (...2s(2)3s). The PES for this B(S-2)... H-2 complex is repulsive and nonreactive, at le ast in the region sampled by vertical electronic excitation of the B(P -2)... H-2 complex. (C) 1995 American Institute of Physics.