Regensburg 2010 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 7: Intermetallic Phases I
MM 7.3: Talk
Monday, March 22, 2010, 10:45–11:00, H5
Ab-initio optimization of the crystal structure ksi and ksi* in Al- Mn-Pd — •Alejandro Santana Bonilla1,2, Michael Engel3, Hans-Rainer Trebin1, and Marek Mihalkovic4 — 1Universität Stuttgart, Institut für Theoretische und Angewandte Physik, 70550 Stuttgart — 2Grupo de sistemas complejos, Universidad Antonio Nariño, Bogotá, Colombia — 3University of Michigan, Ann Arbor, MI, USA — 4Institute of Physics, Slovak Academy of Sciences, 84511 Bratislava, Slovakia
A structural model is given for two approximants, ksi and ksi*, of the decagonal Al-Mn-Pd phase. Both structures were shown to be completely described by two sorts of interpenetrating clusters, namely *Distorted Bergman Cluster* (DBC) and by *Pseudo Mackay Cluster*(PMC). On the basis of these two atomic clusters the two phases can be characterized as some simple periodic tiling of assembly of the column clusters projected onto the plane perpendicular to the 1.6 nm stacking axis. From crystallographic studies the skeleton of heavy atoms was fully described, whereas the inner shell from PMC was poorly detailed. The structural models have been investigated using ab initio and molecular dynamics numerical methods. For this study, suitable improved pair potentials were used in order to determine the ideal cluster structure and the interactions between adjacent clusters. Plausibility of the suggested structures was tested using competing crystalline phases obtained through convex hull calculations and allowing us to suggest a reliable atomic model for the inner shell of the PMC.