VIBRATIONAL ANALYSIS OF A HYLLERAAS-CONFIGURATION INTERACTION POTENTIAL FOR H-3+

The potential surface for H3+, obtained from Hylleraas configuration interaction calculations by Frye et al. [J. Chem. Phys. 92, 4948 (1990)], has been fitted to a seventh-degree polynomial in Morse-Dunham coordinates to study the low-lying vibrational states of H3+, D3+, H2D+, D2H+, H2T+, and T2H+. Vibrational levels of up to two quanta excitations are reported and compared with experiments and other theoretical calculations. There are indications that adiabatic corrections may be important in correcting the small errors in the calculated vibrational quanta. The exothermicity of the proton-transfer reaction between H-2 and H2+ predicted is 1.685 eV, to be compared with the experimental value of 1.7 eV. The calculated dissociation energy for H3+ is 4.337 +/- 0.002 eV, 355 cm-1 smaller than the experimental value of 4.381 +/- 0.021 eV. No source of discrepancy from theoretical side can be identified.