Vibrational entropy of dislocations in Al
2004 (English)In: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 84, no 6, 521-532 p.Article in journal (Refereed) Published
The region nearest to a lattice defect must be described by an atomistic model, while a continuum model suffices further away from the defect. We study such a separation into two regions for an edge dislocation. In particular we focus on the excess defect energy and vibrational entropy, when the dislocation core is described by a cluster of about 500-100 atoms, embedded in a large discrete and relaxed, but static, lattice. The interaction between the atoms is given by a potential of the embedded-atom model type referring to Al. The dynamic matrix of the vibrations in the cluster is fully diagonalized. The excess entropy DeltaS near the core has positive and negative contributions, depending on the sign of the local strain. Typically, DeltaS/k(B) approximate to 2 per atomic repeat length along the dislocation core in fcc Al. In the elastic continuum region far from the dislocation core the excess entropy shows the same logarithmic divergence as the elastic energy. Although the work refers to a specific material and defect type, the results are of a generic nature.
Place, publisher, year, edition, pages
2004. Vol. 84, no 6, 521-532 p.
1st-principles calculations, aluminum, potentials, metals, copper
IdentifiersURN: urn:nbn:se:kth:diva-23106DOI: 10.1080/14786430310001635422ISI: 000188327500002ScopusID: 2-s2.0-1242352398OAI: oai:DiVA.org:kth-23106DiVA: diva2:341804
QC 201005252010-08-102010-08-102010-10-13Bibliographically approved