LeRoy-Bernstein theory is a semi-classical (WKB) approach for describing vibrational energy levels near the molecular dissociation limit.[1] In this limit, the interaction potential between two atoms can be approximated as V ( r ) = D − C n / r n {\displaystyle V(r)={\mathfrak {D}}-C_{n}/r^{n}} , which gives rise to a simple analytical approximation for the vibrational energy levels: