Combined energy–diffraction data refinement of decagonal AlNiCo

Abstract

We incorporate realistic pair-potential energies directly into a non-linear least-square fit of diffraction data to quantitatively compare structure models with experimental data for the Ni-rich d(AlNiCo) quasicrystal. The initial structure models are derived from a few a priori assumptions (gross features of the Patterson function) and the pair-potentials. In place of the common hyperspace approach to the structure refinement of quasicrystals, we use a real-space tile-decoration scheme, which does not rely on strict quasiperiodicity, and makes it easy to enforce sensible local arrangements of the atoms. Inclusion of the energies provides information complementary to the diffraction data and protects the fit procedure from converging on spurious solutions. The method pinpoints sites that are likely to break the symmetry of their local environment.