The potential energy function for the force between two atoms in a diatomic molecule is approximately given by u(x) = a/x12 - b/x6 ,where aand b are constants and x is the distance between the atoms. If the dissociation energy of the molecule is D = [U(x = ∞) – Uat equilibrium], D is
(a) b2/6a
(b) b2/2a
(c)b2/12a
(d)b2/4
