  We investigate the interplay of particle number, N, and structural properties
of selected clusters with N=12 up to N=562 by employing Gupta potentials
parameterized for Aluminum and extensive Monte-Carlo simulations. Our analysis
focuses on closed shell structures with extra atoms. The latter can put the
cluster under a significant stress and we argue that typically such a strained
system exhibits a reduced energy barrier for (surface) diffusion of cluster
atoms. Consequently, also its surface melting temperature, T_S, is reduced, so
that T_S separates from and actually falls well below the bulk value. The
proposed mechanism may be responsible for the suppression of the surface
melting temperature observed in a recent experiments.
