Accurate Kohn–Sham ionization potentials from scaled‐opposite‐spin second‐order optimized effective potential methods

Abstract

One important property of Kohn-Sham (KS) density functional theory is the exact equality of the energy of the highest occupied KS orbital (HOMO) with the negative ionization potential of the system. This exact feature is out of reach for standard density-dependent semilocal functionals. Conversely, accurate results can be obtained using orbital-dependent functionals in the optimized effective potential (OEP) approach. In this article, we investigate the performance, in this context, of some advanced OEP methods, with special emphasis on the recently proposed scaled-opposite-spin OEP functional. Moreover, we analyze the impact of the so-called HOMO condition on the final quality of the HOMO energy. Results are compared to reference data obtained at the CCSD(T) level of theory. © 2016 Wiley Periodicals, Inc.

Investigation of the Exchange-Correlation Potentials of Functionals Based on the Adiabatic Connection Interpolation

“…Indeed, several modifications of OEP-GL2, such as OEP2-sc, OEP2-SOSb, and OEP2-SOS(opt), have been developed to account for this problem. 8,[53][54][55]75 Thus, the partial correction of this drawback from the ACMs is a very promising feature of these functionals which allows them to yield potentials close to the accurate OEP ones (see Fig. 5 where we compare, for the Ne atom, ISI and SPL with OEP2-sc, OEP2-SOSb, OEP2-SOS(opt) as well as with OEP-ccpt2 10 ).…”

Unveiling the Physics Behind Hybrid Functionals

“…In case of HOMO, LUMO and HOMO–LUMO gaps results, we report additionally the mean absolute RE (MARE) calculated with respect to the reference data. 47 , 94…”

Challenges for semilocal density functionals with asymptotically nonvanishing potentials

“…These semilocal density functionals, which only depend on the electron density n(r) and its spatial derivatives, e.g., |∇n(r)|, can provide an overall reasonable accuracy for E xc . Yet their functional derivatives, i.e., the corresponding xc potentials, typically completely miss important features of the exact xc potential [6][7][8][9][10][11][12][13][14][15]. Among them are, e.g., the particle-number discontinuity [16,17] and step structures or steepening effects [8,[18][19][20][21][22][23] that enforce [24], e.g., the principle of integer preference.…”