An improved reliability factor for quantitative low-energy electron diffraction

Area of Science:

• Surface Science
• Materials Science
• Condensed Matter Physics

Background:

• Quantitative low-energy electron diffraction (LEED I(V)) is crucial for determining surface structures by analyzing electron diffraction intensities as a function of electron energy.
• Current analysis relies on optimizing agreement between experimental and calculated intensities, commonly using Pendry's R_P metric.
• Pendry's R_P metric has significant limitations, including sensitivity to noise and intensity offsets, and can yield false positives for agreement.

Purpose of the Study:

• To introduce a modified R_S metric as a superior alternative to Pendry's R_P for LEED I(V) analysis.
• To address the shortcomings of R_P, such as its noisy nature and susceptibility to minor data variations.
• To evaluate the performance of R_S in comparison to R_P and R_ZJ under imperfect experimental conditions.

Main Methods:

• Development and implementation of a modified R_S agreement metric for LEED I(V) data analysis.
• Comparative analysis of R_S, Pendry's R_P, and Zanazzi-Jona's R_ZJ metrics.
• Optimization simulations using experimental LEED I(V) data with introduced imperfections.

Main Results:

• The proposed R_S metric effectively replaces R_P, overcoming its limitations in optimization and sensitivity.
• R_S demonstrates comparable or superior performance to R_P in guiding optimization towards correct surface structures, even with noisy experimental data.
• The R_ZJ metric was found to be less effective than R_S and R_P when dealing with imperfect experimental data.

Conclusions:

• The R_S metric offers a more robust and reliable approach for quantitative surface structure determination using LEED I(V).
• R_S provides a better target function for optimization, reducing the likelihood of erroneous structural assignments.
• This advancement enhances the precision and reliability of surface structure analysis in materials science and surface physics.