Examining the role of pseudopotentials in exact-exchange-based Kohn-Sham gaps

We present exact-exchange calculations of the Kohn-Sham gap, as well as the fundamental gap resulting from it, using highly accurate grid-based all-electron and pseudopotential approaches for prototypical diatomic molecules. Results obtained with pseudopotentials that have been constructed in a manner consistent with the exact-exchange functional agree with the all electron results for the cases studied. This confirms the reliability of the pseudopotential approximation for orbital-dependent functionals such as exact exchange.