  We report on calculations of the elastic cross section and thermalization
rate for collision between two maximally spin-polarized chromium atoms in the
cold and ultracold regimes, relevant to buffer-gas and magneto-optical cooling
of chromium atoms. We calculate ab initio potential energy curves for Cr2 and
the van der Waals coefficient C6, and construct interaction potentials between
two colliding Cr atoms. We explore the effect of shape resonances on elastic
cross section, and find that they dramatically affect the thermalization rate.
Our calculated value for the s-wave scattering length is compared in magnitude
with a recent measurement at ultracold temperatures.
