The rovibrational excitation of H2 induced by H

Cross sections have been computed for rovibrational transitions of H-2, induced by collisions with H atoms, using the H-H-2 interaction potential calculated recently by Mielke et al and an earlier potential of Boothroyd et al. We compare cross sections derived using a simple harmonic oscillator approximation to the vibrational motion with results obtained using numerically 'exact' solutions of the rovibrational eigenvalue equation. We also investigate the convergence of the cross sections with respect to the size of the rovibrational basis set. Convergence is found to be slow, owing to the strength of the collisional coupling between vibrational manifolds.