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A Practicable Real‐Space Measure and Visualization of Static Electron‐Correlation Effects
Author(s) -
Grimme Stefan,
Hansen Andreas
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201501887
Subject(s) - scalar (mathematics) , electron , scalar field , electronic correlation , measure (data warehouse) , statistical physics , visualization , molecule , physics , space (punctuation) , field (mathematics) , mathematics , quantum mechanics , chemistry , computer science , data mining , geometry , pure mathematics , operating system
The inclusion of dynamical and static electron correlation (SEC) is mandatory for accurate quantum chemistry (QC). SEC is particularly difficult to calculate and hence a qualitative understanding is important to judge the applicability of approximate QC methods. Existing scalar SEC diagnostics, however, lack the important information where the SEC effects occur in a molecule. We introduce an analysis tool based on a fractional occupation number weighted electron density ( ρ FOD ) that is plotted in 3D for a pre‐defined contour surface value. The scalar field is obtained by finite‐temperature DFT calculations with pre‐defined electronic temperature (e.g. TPSS at 5000 K). FOD plots only show the contribution of the “hot” (strongly correlated) electrons. We discuss illustrative plots for a broad range of chemical systems from small molecules to large conjugated molecules with polyradicaloid character. Spatial integration yields a single number which can be used to globally quantify SEC.