Potential Energy Surfaces

Adiabatic representation Representation in which the electronic wave functions are calculated for fixed (i.e., nonmoving) nuclei. Avoided intersection Case in which two potential energy surfaces come together but do not intersect. Conical intersection Case in which two potential energy surfaces intersect such that their separation decreases to zero linearly in the relevant nuclear coordinates. Diabatic representation Representation in which the electronic wave function is not adiabatic. Dunham expansion Taylor series expansion of a potential energy curve in the vicinity of its minimum. Electron affinity Binding energy of an electron to a neutral atom or molecule. Equilibrium configuration Geometry of a molecule’s nuclear framework corresponding to the minimum adiabatic energy. Force field The gradient of the potential energy surface. Glancing intersection Case in which two potential energy surfaces intersect such that their separation decreases to zero quadratically in the relevant nuclear coordinates. Ionization energy Energy required to remove an electron from an atom or molecule.