Learning Interatomic Force Coefficients from X-ray Thermal Diffuse Scattering Data

TL;DR

This paper introduces an automated method to extract interatomic force constants from X-ray thermal diffuse scattering data, improving efficiency and accuracy in studying lattice dynamics.

Contribution

It formulates scattering intensity as a differentiable function of IFCs, enabling gradient-based optimization and faster inversion without repeated diagonalizations.

Findings

Accurately recovers ground-truth IFCs and phonon dispersion relations.

Significantly accelerates the inversion process compared to traditional methods.

Provides a high-throughput approach for analyzing lattice dynamics.

Abstract

We present a fully automated framework for extracting interatomic force constants (IFCs) directly from X-ray thermal diffuse scattering (TDS) data. By formulating scattering intensity as a differentiable function of a symmetry-reduced IFC parameterization, we enable gradient-based optimization via direct, Cholesky-based sampling of correlated atomic displacements at thermal equilibrium. This approach bypasses the computational bottleneck of repeated Hessian matrix diagonalizations, significantly accelerating the inversion process. Benchmark tests demonstrate that the framework accurately recovers ground-truth IFCs and phonon dispersion relations, providing a robust, high-throughput pathway for studying lattice dynamics across diverse crystalline materials. This method bridges the gap between experimental observations and computational modeling, enabling the direct integration of TDS data into the refinement of high-fidelity inter-atomic potentials.