Morse Potential

The potential of Morse (blue) and harmonic oscillator potential (green). Unlike the energy levels of the harmonic oscillator potential, which are equispaced by ω, the space between the levels of the Morse potential decreases as the energy approaches the bond dissociation energy. The dissociation energy De is greater than the true energy required for the D0 dissociation due to the zero point energy of the lowest vibrational level (v = 0).

Morse's potential, named after physicist Philip M. Morse, is a convenient model for the potential energy of a diatomic molecule. It is a better approximation for the vibrational structure of the molecule than the quantum harmonic oscillator because it explicitly includes the effects of link rupture, such as the existence of unlinked states. It also accounts for the anharmonicity of the actual links and the non-zero transition probability for the overtones and the combination bands.

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