  Based on a recently introduced metric for measuring distances between
configurations, we in- troduce distance-energy (DE) plots to characterize the
potential energy surface (PES) of clusters. Producing such plots is
computationally feasible on the density functional (DFT) level since it re-
quires only a set of a few hundred stable low energy configurations including
the global minimum. By comparison with standard criteria based on
disconnectivity graphs and on the dynamics of Lennard- Jones clusters we show
that the DE plots convey the necessary information about the character of the
potential energy surface and allow to distinguish between glassy and non-glassy
systems. We then apply this analysis to real systems on the DFT level and show
that both glassy and non-glassy clusters can be found in simulations. It
however turns out that among our investigated clusters only those can be
synthesized experimentally which exhibit a non-glassy landscape.
