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The influence of refinement strategies on the wavefunctions derived from an experiment
Author(s) -
Landeros-Rivera Bruno,
Contreras-García Julia,
Dominiak Paulina M.
Publication year - 2021
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520621008258
Subject(s) - wave function , computation , weighting , experimental data , algorithm , chemistry , computational chemistry , mathematics , computer science , physics , quantum mechanics , statistics , acoustics
The synergy between theory and experiment found in X‐ray wavefunction refinement (XWR) makes it one of the most compelling techniques available for chemical physics. The foremost benefit of XWR – obtaining wavefunctions constrained to experimental data – is at the same time its Achilles heel, because of the dependence of the results on the quality of both empirical and theoretical data. The purpose of this work is to answer the following: What is the effect of the refinement strategy and manipulation of input data on the physical properties obtained from XWR? With that in mind, cutoffs based on data resolution and F /σ( F ) ratios were applied for both steps of XWR, the Hirshfeld atom refinement (HAR) and the X‐ray constrained wavefunction fitting (XCW), for four selected systems: sulfur dioxide, urea, carbamazepine and oxalic acid. The effects of changing the weighting scheme or the method to transform σ( F 2 ) to σ( F ) were also analysed. The results show that while HAR always reaches the same result, XCW is extremely sensitive to crystallographic data manipulation. This is a result of the variability of the experimental uncertainties for different resolution shells, and of not having proper standard uncertainties. Therefore, the use of distinct constraints for each resolution interval in XCW is proposed to fix this instability.