Vibrational dynamics and thermodynamics of surfaces and nanostructures

Our aim in this article is to present an overview of experimental and theoretical studies of the vibrational dynamics and thermodynamics of a set of nano structured surfaces, nanoparticles. and other surface nanostructures. These include surfaces with regularly spaced steps and kink's (chiral surfaces) of varying local geometry, and terrace width, and nanoparticles with single and multi-rains. Some results for the vibrational dynamics and thermodynamics of two-dimensional adatom islands on low miller index surfaces are also included for comparison and because of their relevance to the process of epitaxial growth. Two distinguishing features emerge from the results obtained for this set of systems with under coordinated atoms in diverse geometrical environments. The calculated phonons spectra show a systematic enhancement of modes at the lower end of the frequency spectrum and characteristic modes appear above the top of the bulk band. The origin of these novel features and their influence on the local vibrational entropy contributions are discussed. The unified behavior in the dynamical properties of these nanoscale materials may be rationalized in terms of the local coordination in these systems in which the constituent fcc metals display a correlation between the bond-length and bond-order. (C) 2004 Elsevier B.V. All rights reserved.