So a better question is at what distance do they annihilate. My impression was it happens when the electron and positron "touch", but since they are point particles, this would happen at d=0, which results in a division by zero.
More specifically, I am wondering what the energy released is when the electromagnetic force is also included in this calculation. In the case where the electron and positron are at a distance d, the energy released would be the mass energy (1.022 MeV) plus the energy that resulted from the...