Sticking lifetime of ultracold CaF molecules in triplet interactions

A six-dimensional potential energy surface is constructed for the spin-polarized triplet state of CaF-CaF by $\mathit{\text{ab}}\mathit{\text{initio}}$ calculations at the CCSD(T) level of theory, followed by Gaussian process interpolation. The potential is utilized to calculate the density of states for this bi alkaline-earth-halogen system where we find the value 0.038 $\mu$K${}^{-1}$, implying a mean resonance spacing of 26 $\mu$K in the collision complex. This value implies an associated Rice-Ramsperger-Kassel-Marcus lifetime of 18 $\mu$s, thus predicting long-lived complexes in collisions at ultracold temperatures.