where E 0 corresponds to a purely chemical, non-electrostatic energy, ∂E/∂q, the first derivative of energy with charge, corresponds to the workfunction at q = 0, ϕ 0 , and the second derivative of energy with q corresponds to the inverse of the capacitance, 1/C. To account for reaction energies, we calculate the energy to go from state 1 to state 2, ∆E 1→2 . This term corresponds to the reaction energy from a DFT calculation (the y-axis of either plot in Figure ). Taking the difference between single state energies for 1 and 2 from Equation gives,