A Surface Mode Description in Relation to the MES results

The experimental observation that one has different Debye temperatures for the three distinct surface sites of the AU55 cluster makes the use of a continuum-model picture for discussing the thermal behavior questionable. Indeed, for such small particle sizes, where the surface structure is so manifest, the use of the concept of surface modes becomes dubious, and is certainly inadequate to explain the observed temperature dependence of the f-factors. None the less, it has proven possible to describe the low temperature specific heat of AU55 quite well using such a continuum-model, when the center-of-mass motion is taken into account [99], 

It is unfortunate that the low temperature EXAFS measurements of Marcus et al. [40] were interpreted without considering the inter-cluster motion, since an independent direct comparison to the MES results would have been useful. 

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