Fractional charge behavior and band gap predictions with the XYG3 type of doubly hybrid density functionals

Neil Qiang Su; Weitao Yang; Paula Mori-Sánchez; Xin Xu

doi:10.1021/jp5029992

Fractional charge behavior and band gap predictions with the XYG3 type of doubly hybrid density functionals

J Phys Chem A. 2014 Oct 2;118(39):9201-11. doi: 10.1021/jp5029992. Epub 2014 Jun 3.

Authors

Neil Qiang Su¹, Weitao Yang, Paula Mori-Sánchez, Xin Xu

Affiliation

¹ Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, MOE Laboratory for Computational Physical Science, Department of Chemistry, Fudan University , Shanghai 200433, China.

PMID: 24844969
DOI: 10.1021/jp5029992

Abstract

In this work, we examine the fractional charge behaviors of doubly hybrid (DH) functionals. By plotting the ground-state energies E and energy derivatives for atoms and molecules with fractional electron numbers N, we directly quantify the delocalization errors of some representative DH functionals such as B2PLYP, XYG3, and XYGJ-OS. Numerical assessments on ionization potentials (IPs), electron affinities (EAs), and fundamental gaps, from either integer number calculations or energy derivative calculations, are provided. It is shown that the XYG3 type of DH functionals gives good agreement between their energy derivatives and the experimental IPs, EAs, and gaps, as expected from their nearly straight line fractional charge behaviors.