Quantum Entanglement and Normal-to-Local Transition in Molecule H₂

Quantum entanglement of two stretches in molecule H₂S is investigated for various initial states in terms of the reduced-density von Neumann entropy and the mean entropy defined by average over time. It is shown that the maximal and the mean entropies of an initial state with local-mode character
are smaller than those with normal-mode character, and the mean entropy displays a maximum near the position of the normal-to-local transition.