X-Ray Calc 3: improved software for simulation and inverse problem solving for X-ray reflectivity

Oleksiy V Penkov; Mingfeng Li; Said Mikki; Alexander Devizenko; Ihor Kopylets

doi:10.1107/S1600576724001031

X-Ray Calc 3: improved software for simulation and inverse problem solving for X-ray reflectivity

J Appl Crystallogr. 2024 Mar 15;57(Pt 2):555-566. doi: 10.1107/S1600576724001031. eCollection 2024 Apr 1.

Authors

Oleksiy V Penkov^{1

2}, Mingfeng Li¹, Said Mikki^{1

3}, Alexander Devizenko⁴, Ihor Kopylets⁴

Affiliations

¹ ZJU-UIUC Institute, Zhejiang University, Haining, Zhejiang 314400, People's Republic of China.
² Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA.
³ Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA.
⁴ National Technical University Kharkiv Polytechnic Institute, Kharkiv 61002, Ukraine.

Abstract

This work introduces X-Ray Calc (XRC), an open-source software package designed to simulate X-ray reflectivity (XRR) and address the inverse problem of reconstructing film structures on the basis of measured XRR curves. XRC features a user-friendly graphical interface that facilitates interactive simulation and reconstruction. The software employs a recursive approach based on the Fresnel equations to calculate XRR and incorporates specialized tools for modeling periodic multilayer structures. This article presents the latest version of the X-Ray Calc software (XRC3), with notable improvements. These enhancements encompass an automatic fitting capability for XRR curves utilizing a modified flight particle swarm optimization algorithm. A novel cost function was also developed specifically for fitting XRR curves of periodic structures. Furthermore, the overall user experience has been enhanced by developing a new single-window interface.

Keywords: Levy flight particle swarm optimization; X-Ray Calc 3; X-ray reflectivity; computer simulations; fitting; inverse problems; periodic multilayer structures; structure reconstruction.

Grants and funding

This work was supported by Zhejiang University/University of Illinois at the Urbana-Champaign Institute and the National Natural Science Fund of China/Research Fund for International Scientists under grant No. 52150610493.