Rotationally induced transitions in small clusters - art. no. 016202

The dynamics of an Ar-6 cluster held together by Lennard-Jones forces is st udied classically. The development of chaotic dynamics is mainly followed b y a calculation of the maximum Lyapunov exponent (MLE). Initial momentum ve ctors are chosen from the eigenvectors of the Hessian of the potential ener gy so that rotating and nonrotating clusters can be studied systematically. It is found that the dependence of MLE on the total energy is considerably different for rotational and vibrational excitations. As the magnitude of the angular momentum increases, sharp transitions in MLE are observed. Thes e transitions are explained in terms of the changes of the topology of the effective rovibrational potential energy surface and the dynamic equilibrat ion between the global and local minima.