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X‐ray constrained wavefunctions based on Hirshfeld atoms. I. Method and review
Author(s) -
Davidson Max L.,
Grabowsky Simon,
Jayatilaka Dylan
Publication year - 2022
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/s2052520622004097
Subject(s) - wave function , context (archaeology) , center (category theory) , atom (system on chip) , overfitting , physics , quantum mechanics , computer science , chemistry , crystallography , artificial intelligence , artificial neural network , embedded system , biology , paleontology
The X‐ray constrained wavefunction (XCW) procedure for obtaining an experimentally reconstructed wavefunction from X‐ray diffraction data is reviewed. The two‐center probability distribution model used to perform nuclear‐position averaging in the original paper [Grimwood & Jayatilaka (2001). Acta Cryst. A 57 , 87–100] is carefully distinguished from the newer one‐center probability distribution model. In the one‐center model, Hirshfeld atoms are used, and the Hirshfeld atom based X‐ray constrained wavefunction (HA‐XCW) procedure is described for the first time, as well as its efficient implementation. In this context, the definition of the related X‐ray wavefunction refinement (XWR) method is refined. The key halting problem for the XCW method – the procedure by which one determines when overfitting has occurred – is named and work on it reviewed.