COLLISIONAL EXCITATION OF H2 MOLECULES BY H-ATOMS

Three-dimensional quasi-classical trajectories on an accurate potential energy surface have been used to determine converged state-to-state rate constants for transitions among the low-energy (nu, j) states of molecular hydrogen as the result of collisions with atomic hydrogen in a warm gas. Where available, fully converged three-dimensional quantum cross sections have been incorporated into the evaluation of the rate constants. The temperature dependence of the rate constants has been parameterized over the temperature range 600-10,000 K. Critical densities and rates for ortho/para interconversion for the low-energy states are given at representative temperatures. Our results are compared with previous evaluations of rate constants for H + H-2. Reactive and nonreactive transitions are considered separately, and the relative importance of various types of transition is discussed.