Calculation of rotational energy transfer rates for HD (v=1) in collisions with thermal HD

State resolved rotational energy transfer rates for HD+HD collisions have been computed using quasiclassical dynamics. One of the HD molecules is given an energy corresponding to v=1 and a specific rotational state, Ji1≤6. The other HD molecule is given a rotational–vibrational energy corresponding to an eigenstate of HD but selected according to a thermal distribution at 300 K. The translational energy is selected according to the appropriate thermal distribution at 300 K. The energy transfer is dominated by translational–rotational energy exchange. The calculated rotational energy transfer rates are compared with the experiments of Chandler and Farrow. Modest agreement is achieved for Ji1≤2. Reasons for the lack of agreement are discussed.