Excitation of the fine-structure transitions of O(3PJ) in collisions with ortho- and para-H2

Ab initio calculations at the SCF and CEPA levels have been performed for the interaction potential between O (3P) and H2 (X1Σg+) at separations in the van der Waals region. Potential curves for 3Σ-, 3Π (collinear approach), 3A2, 3B1, 3B2 (orthogonal approach) and 3A' (45o approach) are presented and used in quantum mechanical close coupling calculations of the cross sections for the de-excitation of fine structure transitions in O (3PJ) by ortho- and para-H2. The rate coefficients for these and the reverse transitions are evaluated for a wide range of temperatures. (author)