Acta Phys. -Chim. Sin. ›› 2018, Vol. 34 ›› Issue (6): 567-580.doi: 10.3866/PKU.WHXB201801261

Special Issue: 密度泛函理论中的化学概念特刊

• PERSPECTIVE • Previous Articles     Next Articles

Perspective: Chemical Information Encoded in Electron Density

Julia CONTRERAS-GARCíA1,*(),Weitao YANG2   

  1. 1 UPMC Univ Paris 06, CNRS, UMR 7616, Laboratoire de Chimie Théorique, case courrier 137, 4 place Jussieu, F-75005, Paris
    2 Department of Chemistry, Duke University, Durham, NC 27708, USA
  • Received:2017-11-22 Published:2018-03-20
  • Contact: Julia CONTRERAS-GARCíA E-mail:contrera@lct.jussieu.fr
  • Supported by:
    the Framework of CALSIMLAB under the Public Grant ANR-11-LABX-0037-01 Overseen by the French National Research Agency (ANR) as Part of the "Investissements d'Avenir" Program(ANR-11-IDEX-0004-02);the National Science Foundation(CHE-1362927);the National Institute of Health, USA(R01-GM061870)

Abstract:

In this perspective, we review the chemical information encoded in electron density and other ingredients used in semilocal functionals. This information is usually looked at from the functional point of view: the exchange density or the enhancement factor are discussed in terms of the reduced density gradient. However, what parts of a molecule do these 3D functions represent? We look at these quantities in real space, aiming to understand the electronic structure information they encode and provide an insight from the quantum chemical topology (QCT). Generalized gradient approximations (GGAs) provide information about the presence of chemical interactions, whereas meta-GGAs can differentiate between the different bonding types. By merging these two techniques, we show new insight into the failures of semilocal functionals owing to three main errors: fractional charges, fractional spins, and non-covalent interactions. We build on simple models. We also analyze the delocalization error in hydrogen chains, showing the ability of QCT to reveal the delocalization error introduced by semilocal functionals. Then, we show how the analysis of localization can help understand the fractional spin error in alkali atoms, and how it can be used to correct it. Finally, we show that the poor description of GGAs of isodesmic reactions in alkanes is due to 1, 3-interactions.

Key words: DFT, Semi-local functional, Electron density, Quantum chemical topology