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The mapping of the local contributions of Fermi and Coulomb correlation into intracule and extracule density distributions

The contributions of the correlated and uncorrelated components of the electron-pair density to atomic and molecular intracule I(r) and extracule E(R) densities and its Laplacian functions ∇2I(r) and ∇2E(R) are analyzed at the Hartree-Fock (HF) and configuration interaction (CI) levels of theory. The topologies of the uncorrelated components of these functions can be rationalized in terms of the corresponding one-electron densities. In contrast, by analyzing the correlated components of I(r) and E(R), namely, IC(r) and EC(R), the effect of electron Fermi and Coulomb correlation can be assessed at the HF and CI levels of theory. Moreover, the contribution of Coulomb correlation can be isolated by means of difference maps between IC(r) and EC(R) distributions calculated at the two levels of theory. As application examples, the He, Ne, and Ar atomic series, the C2-2, N2, O2+2 molecular series, and the C2H4 molecule have been investigated. For these atoms and molecules, it is found that Fermi correlation accounts for the main characteristics of IC(r) and EC(R), with Coulomb correlation increasing slightly the locality of these functions at the CI level of theory. Furthermore, IC(r), EC(R), and the associated Laplacian functions, reveal the short-ranged nature and high isotropy of Fermi and Coulomb correlation in atoms and molecules

© Journal of Chemical Physics, 2000, vol. 113, núm. 7, p. 2530-2543

American Institute of Physics

Author: Fradera i Llinàs, Xavier
Duran i Portas, Miquel
Mestres i López, Jordi
Date: 2000
Abstract: The contributions of the correlated and uncorrelated components of the electron-pair density to atomic and molecular intracule I(r) and extracule E(R) densities and its Laplacian functions ∇2I(r) and ∇2E(R) are analyzed at the Hartree-Fock (HF) and configuration interaction (CI) levels of theory. The topologies of the uncorrelated components of these functions can be rationalized in terms of the corresponding one-electron densities. In contrast, by analyzing the correlated components of I(r) and E(R), namely, IC(r) and EC(R), the effect of electron Fermi and Coulomb correlation can be assessed at the HF and CI levels of theory. Moreover, the contribution of Coulomb correlation can be isolated by means of difference maps between IC(r) and EC(R) distributions calculated at the two levels of theory. As application examples, the He, Ne, and Ar atomic series, the C2-2, N2, O2+2 molecular series, and the C2H4 molecule have been investigated. For these atoms and molecules, it is found that Fermi correlation accounts for the main characteristics of IC(r) and EC(R), with Coulomb correlation increasing slightly the locality of these functions at the CI level of theory. Furthermore, IC(r), EC(R), and the associated Laplacian functions, reveal the short-ranged nature and high isotropy of Fermi and Coulomb correlation in atoms and molecules
Format: application/pdf
Citation: Fradera, X., Duran, M., i Mestres, J. (2000). The mapping of the local contributions of Fermi and Coulomb correlation into intracule and extracule density distributions. Journal of Chemical Physics, 113 (7), 2530-2543. Recuperat 11 febrer 2011, a http://link.aip.org/link/doi/10.1063/1.1305920
ISSN: 0021-9606 (versió paper)
1089-7690 (versió electrònica)
Document access: http://hdl.handle.net/10256/3242
Language: eng
Publisher: American Institute of Physics
Collection: Reproducció digital del document publicat a: http://dx.doi.org/10.1063/1.1305920
Articles publicats (D-Q)
Is part of: © Journal of Chemical Physics, 2000, vol. 113, núm. 7, p. 2530-2543
Rights: Tots els drets reservats
Subject: Argó
Compostos orgànics
Fermi-Coulomb, Correlacions de
Funcional de densitat, Teoria del
Hartree-Fock, Teoria de
Heli
Laplace, Transformacions de
Neó
Compostos de nitrogen
Argon
Density functionals
Fermi-Coulomb correlations
Hartree-Fock theory
Helium
Laplace tranformations
Neon
Nitrogen compounds
Organic compounds
Title: The mapping of the local contributions of Fermi and Coulomb correlation into intracule and extracule density distributions
Type: info:eu-repo/semantics/article
Repository: DUGiDocs

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