Combined energy -- diffraction data refinement of decagonal AlNiCo

TL;DR

This paper presents a novel method for refining decagonal AlNiCo quasicrystal structures by integrating realistic pair potential energies into diffraction data fitting, using a real-space tile decoration scheme that enhances local structure understanding.

Contribution

It introduces a real-space refinement approach incorporating pair potentials, improving structure model accuracy without relying on hyperspace methods.

Findings

The method effectively identifies likely symmetry-breaking sites.

Inclusion of energies prevents convergence to spurious solutions.

The approach offers a complementary perspective to diffraction data.

Abstract

We incorporate realistic pair potential energies directly into a non-linear least-square fit of diffraction data to quantitatively compare structure models with experiment for the Ni-rich $d$(AlNiCo) quasicrystal. The initial structure models are derived from a few {\it 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 which are likely to break the symmetry of their local environment.