Efficient fitting of single-crystal diffuse scattering in interaction space: a mean-field approach

TL;DR

This paper introduces a mean-field method for efficiently fitting single-crystal diffuse scattering data directly to microscopic interaction models, revealing the physics of correlated disorder with robustness to data incompleteness.

Contribution

It presents a novel mean-field approach that simplifies the analysis of diffuse scattering by directly modeling microscopic interactions, improving efficiency and robustness.

Findings

Successfully applied to a toy model of mercury halides

Efficient fitting with few parameters

Robust to incomplete data

Abstract

The diffraction patterns of crystalline materials with strongly-correlated disorder are characterised by the presence of structured diffuse scattering. Conventional analysis approaches generally seek to interpret this scattering either atomistically or in terms of pairwise (Warren--Cowley) correlation parameters. Here we demonstrate how a mean-field methodology allows efficient fitting of diffuse scattering directly in terms of a microscopic interaction model. In this way the approach gives as its output the underlying physics responsible for correlated disorder. Moreover, the use of a very small number of parameters during fitting renders the approach surprisingly robust to data incompleteness, a particular advantage when seeking to interpret single-crystal diffuse scattering measured in complex sample environments. We use as the basis of our proof-of-concept study a toy model based on strongly-correlated disorder in diammine mercury(II) halides.