CAP-DD: Improved Correct Asymptotic Potential GGA with Derivative Discontinuity Treatment

We summarize development and performance of a much-improved non-empirical, constraint-based generalized gradient approximation (GGA) exchange functional which has exchange potentials with correct asymptotic behavior (-1/r). It advances over our original “CAP” [J. Chem. Phys. 142, 054105 (2015)] via derivative discontinuity treatment and removal of a spurious mid-range bump in the exchange potential. The mid- and long-range behavior improvements follow from analysis of all sources of pure (-1/r) asymptotic behavior and constraint-based combination of them. Derivative discontinuity is treated by internally consistent treatment of potential shift and approximate self-interaction correction follows from exact calibration to the H atom. Calculated results for standard molecular tests (heats of formation, ionization potentials, electron affinities, bond lengths, barrier heights, etc.) as well as polarizabilities, hyperpolarizabilities, and treatment of excited states, show that the new CAP-DD in many cases is superior to popular GGA functionals, always is competitive, and is competitive with such semi-empirical hybrids as B3LYP.