Question

What does it means dissociation energy with ZPE and without ZPE? Can you give a formula for both?

Answer 1

The energy levels in a harmonic oscillator are equally spaced. The anharmonicity brings these energy levels together to form a continuum. the energy at which this occurs is the dissociation energy and this coincides with the point at which potential energy function is zero, known as the zero point energy. The dissociation energy can be measured from the bottom of the potential which is the Dissociation energy with ZPE or from the Zero point energy (Dissociation energy without ZPE)

Dissociation energy with ZPE=E(V_max)=  _e²/ 4_ee

Dissociation energy without ZPE =_e²/ 4_ee - E(0)

Here, _e is the vibrational wavenumber and _ee is the anharmonicity