It was recalled that the region nearest to a lattice defect had to be described by using an atomistic model, whereas a continuum model was sufficient when further away from the defect. Such a separation into 2 regions was studied for an edge dislocation. Particular attention was focused on the excess defect energy and vibrational entropy when the dislocation core was described by a cluster of 500 to 100 atoms; embedded in a large discrete and relaxed, but static, lattice. The interaction between the atoms was given by a potential, of embedded-atom model type, for Al. The dynamic matrix of the vibrations in the cluster was fully diagonalized. The excess entropy, ΔS, near to the core had positive and negative contributions; depending upon the sign of the local strain. Typically, ΔS/k was equal to about 2, per atomic repeat length along the dislocation core. In the elastic continuum region far from the dislocation core, the excess entropy exhibited the same logarithmic divergence as the elastic energy. The results were generally applicable.

Vibrational Entropy of Dislocations in Al. M.Forsblom, N.Sandberg, G.Grimvall: Philosophical Magazine, 2004, 84[6], 521-32