The nature of the radical-radical interaction potential in the transition-state region (roughly 2 -5 Å, where the magnitudes of long-range van der Waals and bonding forces are similar) requires the use of multireference methods in the direct potential evaluations. Here, these direct potential evaluations in the VRC-TST calculations were carried out using completeactive-space second-order perturbation theory (CASPT2). Fragments were kept rigid in their asymptotic equilibrium geometries, obtained at the same level of theory. Active spaces for all multireference calculations described in this work were chosen to be (2e,2o), in order to allow the molecule to properly dissociate into fragment radicals at large separations. Based on prior literature on multireference potential energy surfaces using VRC-TST, a real level shift of 0.2 and an ionization potential electron affinity (IPEA) shift of 0.25 eV were used for all complete-active-space calculations.