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Structure determinations for random-tiling quasicrystals

Cornell Affiliated Author(s)

Author

C.L. Henley
V. Elser
M. Mihalkovic

Abstract

How, in principle, could one solve the atomic structure of a quasicrystal, modeled as a random tiling decorated by atoms, and what techniques are available to do it? One path is to solve the phase problem first, obtaining the density in a higher dimensional space which yields the averaged scattering density in 3-dimensional space by the usual construction of an incommensurate cut. A novel direct method for this is summarized and applied to an i(AlPdMn) data set. This averaged density falls short of a true structure determination (which would reveal the typical unaveraged atomic patterns.) We discuss the problematic validity of inferring an ideal structure by simply factoring out a 'perp-space' Debye-Waller factor, and we test this using simulations of rhombohedral tilings. A second, 'unified' path is to relate the measured and modeled intensities directly, by adjusting parameters in a simulation to optimize the fit. This approach is well suited for unifying structural information from diffraction and from minimizing total energies derived ultimately from ab-initio calculations. Finally, we discuss the special pitfalls of fitting random-tiling decagonal phases.

Date Published

Journal

Zeitschrift fur Kristallographie

Volume

215

Issue

10

Number of Pages

553-568,

URL

https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033791249&partnerID=40&md5=aee6dd00a00628e81db41ca9a616568b

Group (Lab)

Veit Elser Group

Funding Source

9632275
9873214

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