To understand these qualitative feature better, we can differentiate Eqn (6) with respect to [I] 0 to obtain Eqn , which represents the slope of the k obs plot. Setting the left-hand side of Eqn to zero and solving for [I] 0 , we can determine that there is a minimum on the k obs curve at we can also discover that the asymptotic slope of the tight-binding k obs plot is equal to k on , as in the classical binding situation represented by Eqn .