Inferring Pattern and Disorder in Close-Packed Structures from X-ray Diffraction Studies, Part II: Structure and Intrinsic Computation in Zinc Sulphide

TL;DR

This paper applies epsilon-machine spectral reconstruction to analyze structure and disorder in zinc sulphide's x-ray diffraction spectra, providing a detailed computational mechanics approach to understand polytypism and phase transitions.

Contribution

It extends the epsilon-machine spectral reconstruction method to zinc sulphide, demonstrating its effectiveness in characterizing disorder and structure in complex crystalline materials.

Findings

Successfully reconstructed the stacking structure of zinc sulphide

Identified intrinsic disorder and phase transition signatures

Validated the method against published diffraction spectra

Abstract

In the previous paper of this series [D. P. Varn, G. S. Canright, and J. P. Crutchfield, Physical Review B, submitted] we detailed a procedure--epsilon-machine spectral reconstruction--to discover and analyze patterns and disorder in close-packed structures as revealed in x-ray diffraction spectra. We argued that this computational mechanics approach is more general than the current alternative theory, the fault model, and that it provides a unique characterization of the disorder present. We demonstrated the efficacy of computational mechanics on four prototype spectra, finding that it was able to recover a statistical description of the underlying modular-layer stacking using epsilon-machine representations. Here we use this procedure to analyze structure and disorder in four previously published zinc sulphide diffraction spectra. We selected zinc sulphide not only for the theoretical interest this material has attracted in an effort to develop an understanding of polytypism, but also because it displays solid-state phase transitions and experimental data is available.