QUASI-CRYSTAL STRUCTURE MODELING

We have developed a package of computer codes for the diffraction refi nement of the tiling-decoration models of decagonal quasicrystals. Sin ce up to now all such refinements have been carried out within hypersp ace approach, we discuss the relationships of the two approaches, emph asizing the fact that the model of quasicrystal is not completely spec ified by assigning chemical identities to a nonperiodically arranged s et of points: in addition, the integral part of the model is the hypot hesis about the physically relevant degrees of freedom, assigned to ea ch of these points. The machinery of the tiling-decoration refinement is illustrated on the case of the decagonal AlPdMn quasicrystal, for w hich we present the results obtained by fit to the single-crystal diff raction data [1]. (C) 1997 Elsevier Science S.A.