Global hybrid exchange energy functional with correct asymptotic behavior of the corresponding potential
A non empirical global hybrid exchange correlation energy functional which leads to an exchange potential with correct asymptotic behavior is presented. The exchange functional combines one fourth of exact exchange with three fourths of the correct asymptotic potential (CAP) generalized gradient approximation functional. It is combined with the Perdew Burke Ernzerhof correlation energy with a slightly modified parameterization so as to cancel the gradient terms of CAP exchange with that of correlation, in the limit of slowly varying density. The resulting global hybrid functional, called CAP0, gives heats of formation, ionization potentials, electron affinities, proton affinities, binding energies of weakly interacting systems, barrier heights for hydrogen and non hydrogen transfer reactions, bond distances, and harmonic frequencies on standard test sets that are competitive with results from other long range corrected, Coulomb attenuated, or global hybrid functionals. In fact, they are generally superior to or competitive with CAM PBE0 and, except for heats of formation, with CAM B3LYP as well. Advantageously, the Rydberg excitation energies from CAP0 are superior to those of other global hybrids and of the long range corrected hybrids. They are similar to those from CAM B3LYP and modestly inferior to the CAM PBE0 errors. For the valence excitations, we did not find substantial differences for all the hybrid functionals considered, while the oscillator strengths from CAP0 are better to those of other global hybrids and comparable to those obtained with long range corrected and Coulomb attenuated hybrids.
Theoretical Chemistry Accounts