Bultinck, Patrick

Cottenier, Stefaan

Van Damme, Sofie

Van Driessche, Isabel

Van Speybroeck, Veronique

Vanpoucke, Danny

English

Ghent University Academic Bibliography

Calculating Hirshfeld-I charges in solids:Implementation, pitfalls and applications.Danny E. P. Vanpoucke, Stefaan Cottenier, Veronique Van SpeybroeckCenter for Molecular Modeling, Ghent University,Technologiepark 903, 9052 Zwijnaarde, BelgiumSofie Van Damme, Patrick Bultinck, Isabel Van DriesscheDept. of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Ghent, BelgiumThe concept of “Atoms in molecules” (AIM) is one of the most successful concepts in chemistry.It states that the properties of a molecule can be considered as simple sums of the properties of itsconstituent atoms. Although a precise definition of an AIM remains elusive, an impressive amountof insight has, over the years, been gained through its usage. The central question in the AIM con-cept is how one should divide the electrons of the system over its constituent “atoms”. Such adivision can be done either in Hilbert-space (e.g. Mulliken population analysis) or in real space(e.g. Bader’s QTAIM). Over the years, many different partitioning schemes have been developedand have been employed in the study of molecules. In recent years, the solid state communityhas started to show an increasing interest in using the AIM concept for the investigation of solids.Bader’s QTAIM approach has received much interest in this context, since this approach is wellsuited for the close packed nature of solids. Recently, also the Hirshfeld and Hirshfeld-I (HI)1partitioning schemes have been implemented for solids. In this scheme the AIM do not have asharp boundary, as in the QTAIM case, instead they have a diffuse boundary allowing for overlapbetween neighboring AIM’s.In this work, we present how the molecular Hirshfeld-I scheme can be extended to (infinite) peri-odic systems, making use of grid stored charge density distributions only,23 since these can easilybe obtained from standard solid state codes. This makes the implementation independent of thebasis set used in the solid state code.We will discuss the (conceptual) problem which occurs during the practical generation of the ref-erence anions, and propose several ways to tackle this problem. Using a large set of benchmarkmolecules, we establish the quality of our implementation, and show the robustness of the parti-tioning scheme.With the method established, we turn our attention to actual solids and large periodic systems. Weshow that the calculated charges allow for the differentiation of oxidation states (e.g. CeIII andCeIV in ceria, and VIII and VIV in different metal organic frameworks (MOFs) ) and inequivalentatomic sites (e.g. graphite and O in Ce2O3).23 We also investigate the propagation of charge trans-fer due to the presence of dopants (e.g. in CeO2) or functional groups (e.g. in the MIL-47 MOF)in the system.4 These few applications show that the Hirshfeld-I AIM is a useful tool in the studyof solids, providing additional insight in the way a system is modified by the presence of defects,interfaces, functional groups etc.1. P. Bultinck, C. Van Alsenoy, P. W. Ayers, et al., J. Chem. Phys. 126 144111 (2007).2. D. E. P. Vanpoucke, P. Bultinck, and I. Van Driessche, J. Comput. Chem. 34 405–417 (2013).3. D. E. P. Vanpoucke, I. Van Driessche, and P. Bultinck, J. Comput. Chem. 34 422–427 (2013).4. D. E. P. Vanpoucke, P. Bultinck, S. Cottenier, et al., submitted (2013)

Calculating Hirschfeld-I charges in solids: implementation, pitfalls and applications

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Calculating Hirschfeld-I charges in solids: implementation, pitfalls and applications

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