Hello I am trying to follow Olson's theory of electron transfer (Ion-Ion Recombination Total Cross Sections-Atomic Species 1970) using Gaussian for ion pair of N+ & O-. However, the result of my calculation gave a large enthalpy change (around 0.376 Hartree). So I was not able to get a reasonable crossing point (I assumed additional potentials are LJ potential and electric potential, the crossing point is less than 1.0 ang which seems contradict to LJ potential). I wonder if there is some conceptual flaws or there is something else I need to pay close attention to in Gaussian. Please give me some suggestions if you have any previous experience on this type of calculation, Thank you so much!