We study collisions of para-${\mathrm{H}}_2$ with five rare-gas atomic species (He, Ne, Ar, Kr, and Xe) over the range from $1\mathrm{K}\text{to}1\mu \mathrm{K}$ and evaluate the feasibility of sympathetic cooling ${\mathrm{H}}_2$ with ultracold ground state rare-gas atoms co-trapped within a deep optical trap. Collision cross sections over this large temperature range show that all of these species could be used to cool ${\mathrm{H}}_2$ to ultracold temperatures and that argon and helium are the most promising species for future experiments. A simple yet accurate method for calculating the microscopic observables needed in the present analysis is also described, as well as the sensitivity of the calculated cross sections to the potential energy surface used.

• Received 10 June 2008

DOI:https://doi.org/10.1103/PhysRevA.78.052707