Rovibrational excitation of HD in collisions with atomic and molecular hydrogen

We have computed cross-sections and rate coefficients for rovibrational transitions in HD, induced by collisions with atomic and molecular hydrogen. We employed fully quantum-mechanical methods and the potential of Boothroyd et al. for H—HD, and that of Schwenke for H2-HD. The rate coefficients for vibrational relaxation v=1→0 of HD are compared with the corresponding values for H2. The influence of vibrationally excited channels on the rate coefficients for rotational transitions within the v=0 vibrational ground state of HD is shown to be small at T=500 K, where T is the kinetic temperature. The rate coefficients, for 100T2000 K, are available from http://ccp7.dur.ac.uk/.