My understanding is that the dipole-dipole interaction strength V is related to the coupling matrix element H as follows (where |i> is the initial state and |f> is the final state):

V = /r^3

I find expressions like this in many papers but I'm not finding many papers that provide some concrete values for this. For instance in biophysics or photovoltaics, what are typical values for common transfer processes (or just a ball park range)?