Clustering of topological defects in superheated metals

The connection between vibrational and topological disorder in superheated crystalline bulks of metallic species is studied. Numerical calculations are employed to study the behavior of metallic lattices in the temperature range between 600 K and the homogeneous melting point. The gradual temperature rise induces not only vibrations of larger amplitude, but also a corresponding increase in the number of atoms with defective coordination. This suggests that vibrational and topological disorders are strongly associated. It appears, indeed, that vibrationally excited atoms are often also defectively coordinated. While randomly dispersed at relatively low temperatures, at temperatures close to the melting point defective and vibrationally excited atoms self-organize in string-like clusters. A marked localization of topological defects in particular regions of solid is thus observed. The results obtained support a defect-mediated melting scenario. (c) 2005 Elsevier B.V. All rights reserved.