Angle-Resolved Lattice Population Density Plots: A Novel Approach for Fast 2D Unit Cell Determination from HAADF STEM Images

This study presents a new efficient method for determining the 2D unit cell size from HAADF STEM images using angle-resolved lattice population density (ALPD) plots. The approach uses the maxima in these plots, which represent the lines with the highest atom peak density, to determine the cell angle of the primitive 2D unit cell. Lattice types and 2D unit cell sizes that comply with crystallographic standards can easily be obtained by introducing angle constraints for the selection of the ALPD maxima. The method is very flexible and can be applied to images with fewer than 20 atom peaks, making it valuable for the automated analysis of periodic lattices in both large and small crystalline regions. The method has been evaluated for ideal and disordered lattices and is compared in terms of processing speed and the quality of results with the recently proposed real-space motif extraction method and with the well-established Fourier-based crystallographic image processing method commonly used for this task.