  The molecular dynamics and Monte Carlo studies of the thermal stability of
C20, C36, and C60 fullerenes and the methane molecule are reported. It has been
shown that the heat transfer between the atomic cluster and the external heat
reservoir can either promote or prohibit the formation of defects in this
cluster. The widen temperature and pressure ranges have been determined where
the defect formation rate is essentially nonArrhenius. It has been shown that
the lifetime of light clusters in molecules depends more strongly on the
contact with the heat reservoir. A statistical model that is based on the
kinetic equation and allows for an analytical solution has been developed to
explain the results. Within this model, the generalized Arrhenius formula has
been derived to predict the lifetime of the clusters in an arbitrary thermal
contact with the environment.
