N‐Representable one‐electron reduced density matrices reconstruction at non‐zero temperatures. Issue 5 (21st September 2021)

• Record Type: Journal Article
• Authors: Launay, Yoann; Gillet, Jean-Michel
• Is Part Of: Acta crystallographica. Volume 77:Issue 5(2021)
• Page Start: 683
• Page End: 694
• Publication Date: 2021-09-21
• Subjects: density matrices -- temperature smearing -- Compton scattering -- X‐ray diffraction -- quantum crystallography
• DOI: 10.1107/S2052520621007228
• Languages: English
• ISSNs: 2052-5206

Abstract

Abstract : This article retraces different methods that have been explored to account for the atomic thermal motion in the reconstruction of N ‐representable one‐electron reduced density matrices from experimental X‐ray structure factors and directional Compton profiles. Abstract : This article retraces different methods that have been explored to account for the atomic thermal motion in the reconstruction of one‐electron reduced density matrices from experimental X‐ray structure factors (XSF) and directional Compton profiles (DCP). Attention has been paid to propose the simplest possible model, which obeys the necessary N ‐representability conditions, while accurately reproducing all available experimental data. The deconvolution of thermal effects makes it possible to obtain an experimental static density matrix, which can directly be compared with theoretical 1‐RDM (reduced density matrix). It is found that above a 1% statistical noise level, the role played by Compton scattering data becomes negligible and no accurate 1‐RDM is reachable. Since no thermal 1‐RDM is available as a reference, the quality of an experimentally derived temperature‐dependent matrix is difficult to assess. However, the accuracy of the obtained static 1‐RDM, through the performance of the refined observables, is strong evidence that the Semi‐Definite Programming method is robust and well adapted to the reconstruction of an experimental dynamical 1‐RDM.