Calculating temperature-dependent X-ray structure factors of α-quartz with an extensible Python 3 package

DOI: 10.1107/S1600576722005945

Authors: John P. Sutter (Diamond Light Source) , James Pittard (University of Bristol) , Jacob Filik (Diamond Light Source) , Alfred Q. R. Baron (RIKEN SPring-8 Center)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Applied Crystallography , VOL 55

State: Published (Approved)
Published: August 2022

Abstract: The design of X-ray optics based on diffraction from crystals depends on the accurate calculation of the structure factors of their Bragg reflections over a wide range of temperatures. In general, the temperature dependence of the lattice parameters, the atomic positions and the atomic thermal vibrations is both anisotropic and nonlinear. Implemented here is a software package for precise and flexible calculation of structure factors for dynamical diffraction. α-Quartz is used as an example because it presents the challenges mentioned above and because it is being considered for use in high-resolution X-ray spectroscopy. The package is designed to be extended easily to other crystals by adding new material files, which are kept separate from the package's stable core. Python 3 was chosen as the language to allow the easy integration of this code into existing packages. The importance of a correct anisotropic treatment of the atomic thermal vibrations is demonstrated by comparison with an isotropic Debye model. Discrepancies between the two models can be as much as 5% for strong reflections and considerably larger (even to the level of 100%) for weak reflections. A script for finding Bragg reflections that backscatter X-rays of a given energy within a given temperature range is demonstrated. The package and example scripts are available on request. Also discussed, in detail, are the various conventions related to the proper description of chiral quartz.

Journal Keywords: quartz; X-rays; structure factors; Python

Subject Areas: Information and Communication Technology, Physics


Technical Areas: Optics

Added On: 01/08/2022 09:19

Documents:
Journal of Applied Crystallography - 2022 - Sutter - Calculating temperature%E2%80%90dependent X%E2%80%90ray structure factors of %E2%80%90quartz.pdf

Discipline Tags:

Optics Physics Computing & software technologies Information & Communication Technologies

Technical Tags: