Sanibel Symposium 2019
St. Simons Island, GA, USA, February 17-22
Exchange energy functional in the generalized gradient approximation with nearly correct asymptotic potential
José L. Gázquez,a, Javier Carmona-Espíndolab, Alberto Velac and S. B. Trickeyd
aUniversidad Autónoma Metropolitana-Iztapalapa, Departamento de Química, Av. San Rafael Atlixco 186, Cd. de México, 09340, México.
bConacyt-Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Química, Av. San Rafael Atlixco 186, Cd. de México, 09340, México.
cCentro de Investigación y de Estudios Avanzados, Departamento de Química, Av. Instituto Politécnico Nacional 2508, Cd. de México, 07360 México.
dUniversity of Florida, Quantum Theory Project, Dept. of Physics and Dept. of Chemistry, P.O. Box 118435, Gainesville, Florida 32611-8435, USA.
A novel and highly effective non-empirical exchange energy density functional of the generalized gradient approximation form has been developed and tested. The analytic expression for the enhancement factor FX (s)(s is the reduced density gradient), when constrained to asymptotic exchange potential behavior, leads to the generalized gradient approximation when s → 0 , and to [(1−ζ )slns −ζ s] when s → ∞ (ζ is a constant). The latter allows one to impose in the variationally determined exchange potential the effects of the derivative discontinuity and a nearly correct asymptotic potential of the form −c / r , where c ∼ 0.3 . The new exchange energy functional combined with the Perdew-86 correlation (J. P. Perdew, Phys. Rev. B 33, 8822 (1986)) provides an accuracy on standard thermochemistry tests equivalent to the one obtained from the meta-GGA SCAN, and from several global hybrids. It also enables time dependent DFT (TD-DFT) calculations of good quality polarizabilities, hyper-polarizabilities, and one-fermion excited states. Additionally, the new functional provides reasonably close satisfaction of the DFT ionization potential theorem.