Dunham expansion
In quantum chemistry, the Dunham expansion is an expression for the rotational-vibrational energy levels of a diatomic molecule:
where v and J are the vibrational and rotational quantum numbers.
The constant coefficients are called Dunham parameters with representing the electronic energy. The expression derives from a semiclassical treatment of a perturbational approach to deriving the energy levels. The Dunham parameters are typically calculated by a least-squares fitting procedure of energy levels with the quantum numbers.This table adapts the sign conventions from the book of Huber and Herzberg.
