Behavior of the Lyapunov Exponent and Phase Transition in Nuclei

Based on the quantum molecular dynamics model,we investigate the dynamical behaviors of the excited nuclear system to simulate the latter stage of heavy ion reactions,which associate with a liquid-gas phase transition.We try to search a microscopic way to describe the phase transition in realnuclei.The Lyapunov exponent is employed and examined for our purpose.We find out that the Lyapunov exponent is one of good microscopic quantities to describe the phase transition in hot nuclei.Coulomb potential and the finite size effect may give a strong influence on the critical temperature.However,the collision term plays a minor role in the process of the liquid-gas phase transition in finite systems.