Converged calculations of rotational energy transfer in HFHF collisions

We have performed large‐scale close coupling calculations of rotational‐to‐rotational energy transfer in HFHF collisions for the realistic potential energy surface of Brobjer and Murrell. We employ up to 525 angular terms in the expansion of the potential and up to 440 coupled channels in the rotational‐orbital basis set. The results for zero total angular momentum are well converged for relative translational energies up to over 0.6 eV, and they show extensive rotational excitation.