Nuclear motion on electronic energy landscapes — the foundation of molecular quantum mechanics
The Born-Oppenheimer approximation separates nuclear and electronic motion. The Morse potential V(r) = De(1−e−α(r−re))² captures anharmonic vibrational states. Each horizontal line is a quantized vibrational level; the wavefunction probability density |ψ|² is shown overlaid. Anharmonicity causes unequal level spacing — dissociation occurs at finite energy De.