is a reasonable surrogate for Γ (eq. 10) in some instances, yet one that based on rigorous expectation values and independent of representation. The first term in eq. 19 (d e-h ) can be seen as a representation-invariant alternative to ∆r, while |σ hole -σ elec | encodes any size disparity between the electron and the hole. In previous work, 1,2 it was speculated that the quantity