Out-of-Time-Order-Correlator in van der Waals potentials

Out-of-time-order correlator (OTOC) is one of the dynamical quantities used to quantify the quantum-to-classical correspondence. The OTOC is expected to grow exponentially at early time in chaotic systems, characteristic of a Lyapunov exponent. However, exponential growth can also occur for integrable systems. Here we present the OTOC for realistic diatomic molecular potentials in one degree of freedom. The results show that the OTOC can grow exponentially near the dissociation energy of the potential, and this dynamics is tied to the classical dynamics of the atoms at the outer classical turning point. These results may serve to guide and interpret dynamical chaos in more complex molecules.