  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.
