Microcanonical temperature and its Arrhenius relation to lifetimes in isomerization dynamics of clusters

Defining the microcanonical temperature as a kinetic energy which maximizes a phase space distribution projected onto the potential energy coordinate, it is shown that this temperature can characterize a time scale of structural isomerization dynamics in the liquid like phase. In particular, it was found that the local microcanonical temperature bears an Arrhenius-type relation to the inverse of the average lifetime in isomerization of M₇ clusters. Thus, with this temperature one can extract critical information hidden behind the stepwise fluctuation of the kinetic energy of a trajectory in an isomerization process. A possible origin of the Arrhenius-type relation is explored.