Pervasive Delocalisation Error Causes Spurious Proton Transfer in Organic Acid–Base Co‐Crystals

Dispersion‐corrected density‐functional theory (DFT‐D) methods have become the workhorse of many computational protocols for molecular crystal structure prediction due to their efficiency and convenience. However, certain limitations of DFT, such as delocalisation error, are often overlooked or are...

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Bibliographic Details
Published in:Angewandte Chemie 2018-11, Vol.130 (45), p.15122-15126
Main Authors: LeBlanc, Luc M., Dale, Stephen G., Taylor, Christopher R., Becke, Axel D., Day, Graeme M., Johnson, Erin R.
Format: Article
Language:English
Subjects:
Acids
Charge transfer
Chemistry
Cokristalle
Computer applications
Crystal structure
Crystals
Density functional theory
Dichtefunktionalrechnungen
Elektronische Strukturen
Ladungstransfer
Molecular structure
Protonation
Salts
Salze
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Summary:Dispersion‐corrected density‐functional theory (DFT‐D) methods have become the workhorse of many computational protocols for molecular crystal structure prediction due to their efficiency and convenience. However, certain limitations of DFT, such as delocalisation error, are often overlooked or are too expensive to remedy in solid‐state applications. This error can lead to artificial stabilisation of charge transfer and, in this work, it is found to affect the correct identification of the protonation site in multicomponent acid–base crystals. As such, commonly used DFT‐D methods cannot be applied with any reliability to the study of acid–base co‐crystals or salts, while hybrid functionals remain too restrictive for routine use. This presents an impetus for the development of new functionals with reduced delocalisation error for solid‐state applications; the structures studied herein constitute an excellent benchmark for this purpose. Eine oft übersehene Einschränkung der Dichtefunktionaltheorie, der Delokalisierungsfehler, manifestiert sich bei den Protonierungsstellen in Säure‐Base‐Mehrkomponentenkristallen. Durch diesen Fehler erscheint die Zuverlässigkeit solcher Methoden für die Validierung experimenteller (und die Vorhersage neuer) Kristallstrukturen zweifelhaft. Für einen routinemäßigen Einsatz in der Industrie sollten daher alternative Methoden entwickelt werden.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201809381