Nonadiabatic corrections to the lowest EF (1)Sigma(g) and I-1 Pi(-)(g) vibrational levels of the hydrogen-molecule

EF (1) Sigma(g), and I (1) Pi(g)(-) electronic states of molecular hydrogen are investigated and nonadiabatic db initio energies of lower lying vibrational levels of H-2, D-2, and T-2 are computed. The resulting term values are compared with experiment and existing theoretical results. For the I-state and the EF-state levels, with energies below -0.675 a.u., the remaining discrepancies with experiment do not exceed +/-0.5 cm(-1). The origin of the residual errors is briefly discussed. (C) 1996 American Institute of Physics.