Approximating the Shifted Hartree-Exchange-Correlation Potential in Direct Energy Kohn–Sham Theory

• Published in: Journal of chemical theory and computation Vol. 14; no. 2; pp. 684 - 692
• Main Authors: Sharpe, Daniel J, Levy, Mel, Tozer, David J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 13.02.2018
• Subjects: Density functional theory; Electron gas; Exchanging; Gas analysis; Mathematical analysis; Molecular chains
• ISSN: 1549-9618; 1549-9626
• DOI: 10.1021/acs.jctc.7b01060

Levy and Zahariev [Phys. Rev. Lett. 113 113002 (2014)] have proposed a new approach for performing density functional theory calculations, termed direct energy Kohn–Sham (DEKS) theory. In this approach, the electronic energy equals the sum of orbital energies, obtained from Kohn–Sham-like orbital equations involving a shifted Hartree-exchange-correlation potential, which must be approximated. In the present study, density scaling homogeneity considerations are used to facilitate DEKS calculations on a series of atoms and molecules, leading to three nonlocal approximations to the shifted potential. The first two rely on preliminary Kohn–Sham calculations using a standard generalized gradient approximation (GGA) exchange-correlation functional and the results illustrate the benefit of describing the dominant Hartree component of the shift exactly. A uniform electron gas analysis is used to eliminate the need for these preliminary Kohn–Sham calculations, leading to a potential with an unconventional form that yields encouraging results, providing strong motivation for further research in DEKS theory.