  A six-dimensional potential energy surface is constructed for the
spin-polarized triplet state of CaF-CaF by \textit{ab 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.
