MPFit: A robust method for fitting atomic resolution images with multiple Gaussian peaks

TL;DR

MPFit is a new atom-finding algorithm that improves accuracy and robustness in fitting atomic resolution images by iteratively fitting overlapping Gaussian peaks, outperforming traditional single-peak methods especially in challenging imaging conditions.

Contribution

Introduces MPFit, an iterative overlapping Gaussian fitting method that enhances atom position estimation accuracy and robustness in atomic resolution microscopy images.

Findings

Lower fitting errors compared to single Gaussian methods

Increased robustness across various experimental conditions

Effective in images with aberrations and strong intensity variations

Abstract

The standard technique for sub-pixel estimation of atom positions from atomic resolution scanning transmission electron microscopy images relies on fitting intensity maxima or minima with a two-dimensional Gaussian function. While this is a widespread method of measurement, it can be error prone in images with non-zero aberrations, strong intensity differences between adjacent atoms or in situations where the neighboring atom positions approach the resolution limit of the microscope. Here we demonstrate mpfit, an atom finding algorithm that iteratively calculates a series of overlapping two-dimensional Gaussian functions to fit the experimental dataset and then subsequently uses a subset of the calculated Gaussian functions to perform sub-pixel refinement of atom positions. Based on both simulated and experimental datasets presented in this work, this approach gives lower errors when compared to the commonly used single Gaussian peak fitting approach and demonstrates increased robustness over a wider range of experimental conditions.