A General Quasi-Periodic Sampling Method for Simulating and Interpreting X-ray Powder Diffraction Patterns of Ultrathin Crystalline Materials.

The characterization of ultrathin crystalline materials remains challenging because of their unique structural features, which limit the application of conventional X-ray powder diffraction (PXRD). Here, we present a general quasi-periodic sampling (QPS) method for accurately simulating and interpreting the PXRD patterns of such materials. The approach reconstructs diffraction signals by transforming low-dimensional crystals into three-dimensional periodic systems through the introduction of a pseudo-superlattice and a sufficiently thick vacuum layer. This modeling approach is compatible with most standard PXRD simulation software. Using this method, we systematically investigated close-packed metals, two-dimensional metal-organic frameworks (2D MOFs), and diverse inorganic layered materials to establish relationships between atomic structures and PXRD patterns. This work provides a cost-effective and reliable computational tool for structural analysis of ultrathin crystalline materials, with broad applicability in the rational design of such systems.