Adding another cation into the cells creates three distinct pathways of diffusion for each occupational site in the system because of symmetry: The first where the diffusing atom diffuses away from the other cation, the second where it diffuses towards and then the third where the diffusing cation moves parallel to the other cation, which lies in the other half of the unit cell along the z axis and thus has maximum distance to the diffusion pathway. These three environments are present for all six pathways in the large rhombohedral unit cell. We performed the calculations for the three environments using only one of the six pathways because the calculations with one cation showed those six to be energetically equivalent. As described before, they are asymmetrical pathways where the higher barrier is the determining step. Both isostructural cells (with Ti or Zr) showed the same trend: The closer the additional cation is to the diffusion process, the higher the barrier gets. For the Ti phase the barriers where the cation diffuses towards and away from the additional cation the barriers both lie at 1.01 eV and when the cation is further away on the parallel, the barrier is 0.89 eV. For the Zr phase the farther barriers are 0.76 eV and the closer one is 0.61 eV.