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Open AccessArticle

Optimized Atomic Partial Charges and Radii Defined by Radical Voronoi Tessellation of Bulk Phase Simulations

Institut für Chemie, Martin-Luther-Universität Halle–Wittenberg, von-Danckelmann-Platz 4, D-06120 Halle (Saale), Germany
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Academic Editor: Stacey Wetmore
Molecules 2021, 26(7), 1875; https://doi.org/10.3390/molecules26071875
Received: 28 February 2021 / Revised: 22 March 2021 / Accepted: 24 March 2021 / Published: 26 March 2021
(This article belongs to the Special Issue Describing Bulk Phase Effects with Ab Initio Methods)
We present a novel method for the computation of well-defined optimized atomic partial charges and radii from the total electron density. Our method is based on a two-step radical Voronoi tessellation of the (possibly periodic) system and subsequent integration of the total electron density within each Voronoi cell. First, the total electron density is partitioned into the contributions of each molecule, and subsequently the electron density within each molecule is assigned to the individual atoms using a second set of atomic radii for the radical Voronoi tessellation. The radii are optimized on-the-fly to minimize the fluctuation (variance) of molecular and atomic charges. Therefore, our method is completely free of empirical parameters. As a by-product, two sets of optimized atomic radii are produced in each run, which take into account many specific properties of the system investigated. The application of an on-the-fly interpolation scheme reduces discretization noise in the Voronoi integration. The approach is particularly well suited for the calculation of partial charges in periodic bulk phase systems. We apply the method to five exemplary liquid phase simulations and show how the optimized charges can help to understand the interactions in the systems. Well-known effects such as reduced ion charges below unity in ionic liquid systems are correctly predicted without any tuning, empiricism, or rescaling. We show that the basis set dependence of our method is very small. Only the total electron density is evaluated, and thus, the approach can be combined with any electronic structure method that provides volumetric total electron densities—it is not limited to Hartree–Fock or density functional theory (DFT). We have implemented the method into our open-source software tool TRAVIS. View Full-Text
Keywords: atomic partial charges; Voronoi tessellation; molecular dynamics; electron structure theory; numerical integration; non-linear optimization; bulk phase; liquid phase; hydrogen bond atomic partial charges; Voronoi tessellation; molecular dynamics; electron structure theory; numerical integration; non-linear optimization; bulk phase; liquid phase; hydrogen bond
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MDPI and ACS Style

Brehm, M.; Thomas, M. Optimized Atomic Partial Charges and Radii Defined by Radical Voronoi Tessellation of Bulk Phase Simulations. Molecules 2021, 26, 1875. https://doi.org/10.3390/molecules26071875

AMA Style

Brehm M, Thomas M. Optimized Atomic Partial Charges and Radii Defined by Radical Voronoi Tessellation of Bulk Phase Simulations. Molecules. 2021; 26(7):1875. https://doi.org/10.3390/molecules26071875

Chicago/Turabian Style

Brehm, Martin; Thomas, Martin. 2021. "Optimized Atomic Partial Charges and Radii Defined by Radical Voronoi Tessellation of Bulk Phase Simulations" Molecules 26, no. 7: 1875. https://doi.org/10.3390/molecules26071875

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