Potential energy surfaces for and energetics of the weakly-bound Al-H-2 and B-H-2 complexes

摘要

Following an earlier investigation [M. H. Alexander, J. Chem. Phys. 99, 6014 (1993)] of the B(2s(2)2p P-2)-H-2 complex, we report new ground state potential energy surfaces (PESs) for the Al(2s(2)2p P-2)-H-2 and B(2s(2)2p P-2)-H-2 van der Waals complexes, based on multireference configuration-interaction calculations with an extrapolation to the complete basis set limit. The degeneracy of the Al 3p and B 2p orbitals gives rise to three adiabatic PESs (two of A' symmetry and one of A' symmetry in C-s geometry). By viewing the two adiabatic states of A' symmetry as an orthogonal transformation of the in-plane Al 3p and B 2p orbitals, we transform the PESs to an approximate diabatic representation, which involves four potential energy functions. Both molecules have energy minima in C-2v geometry with an electronic symmetry B-2(2). The dissociation energies are D-e = 231 cm(-1) for Al-H-2 and 142 cm(-1) for B-H-2. The energies of the lowest bend-stretch levels of the complexes of Al (P-2) and B (P-2) with either o- or pH(2) are determined from the diabatic PESs. The predicted zero-point-corrected dissociation energies (D-0) are 49.2 and 74.3 cm(-1) for Al with pH(2) and oH(2), respectively, and 39.7 and 59.8 cm(-1) for B with pH(2) and oH(2), respectively. (C) 2000 American Institute of Physics. [S0021-9606(00)30213-6]. [References: 40]