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Author Hartman, Joshua D. ♦ Beran, Gregory J. O. ♦ Monaco, Stephen ♦ Schatschneider, Bohdan
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ APPROXIMATIONS ♦ CHEMICAL SHIFT ♦ CLUSTER MODEL ♦ HYBRIDIZATION ♦ MOLECULAR CRYSTALS ♦ NUCLEAR MAGNETIC RESONANCE ♦ POLARIZATION ♦ TENSORS
Abstract We assess the quality of fragment-based ab initio isotropic {sup 13}C chemical shift predictions for a collection of 25 molecular crystals with eight different density functionals. We explore the relative performance of cluster, two-body fragment, combined cluster/fragment, and the planewave gauge-including projector augmented wave (GIPAW) models relative to experiment. When electrostatic embedding is employed to capture many-body polarization effects, the simple and computationally inexpensive two-body fragment model predicts both isotropic {sup 13}C chemical shifts and the chemical shielding tensors as well as both cluster models and the GIPAW approach. Unlike the GIPAW approach, hybrid density functionals can be used readily in a fragment model, and all four hybrid functionals tested here (PBE0, B3LYP, B3PW91, and B97-2) predict chemical shifts in noticeably better agreement with experiment than the four generalized gradient approximation (GGA) functionals considered (PBE, OPBE, BLYP, and BP86). A set of recommended linear regression parameters for mapping between calculated chemical shieldings and observed chemical shifts are provided based on these benchmark calculations. Statistical cross-validation procedures are used to demonstrate the robustness of these fits.
ISSN 00219606
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-09-14
Publisher Place United States
Journal Journal of Chemical Physics
Volume Number 143
Issue Number 10


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