PW86-PW91 density functional calculation of vertical ionization potentials: Some implications for present-day functionals

Shapley, Warwick A.; Chong, Delano P.

doi:10.1002/1097-461x(2001)81:1<34::aid-qua7>3.0.co;2-8

Cited by 27 publications

(12 citation statements)

References 41 publications

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“…For example, many generalized gradient approximation functionals did poorly on perhalo molecules, as discovered earlier. 65 If the three perhalo molecules were excluded, then better choices would be PBE and mPBE.…”

Section: Resultsmentioning

confidence: 99%

Density functional study of double ionization energies

Chong

2008

The Journal of Chemical Physics

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In this paper, double ionization energies (DIEs) of gas-phase atoms and molecules are calculated by energy difference method with density functional theory. To determine the best functional for double ionization energies, we first study 24 main group atoms in the second, third, and fourth periods. An approximation is used in which the electron density is first obtained from a density functional computation with the exchange-correlation potential V xc known as statistical average of orbital potentials, after which the energy is computed from that density with 59 different exchange-correlation energy functionals E xc. For the 24 atoms, the two best E xc functional providing DIEs with average absolute deviation (AAD) of only 0.25 eV are the Perdew-Burke-Ernzerhof functional modified by Hammer et al. [Phys. Rev. B 59, 6413 (1999)] and one known as the Krieger-Chen-Iafrate-Savin functional modified by Krieger et al. (unpublished). Surprisingly, none of the 20 available hybrid functionals is among the top 15 functionals for the DIEs of the 24 atoms. A similar procedure is then applied to molecules, with opposite results: Only hybrid functionals are among the top 15 functionals for a selection of 29 molecules. The best E xc functional for the 29 molecules is found to be the Becke 1997 functional modified by Wilson et al. [J. Chem. Phys. 115, 9233 (2001)]. With that functional, the AAD from experiment for DIEs of 29 molecules is just under 0.5 eV. If the two suspected values for C2H2 and Fe(CO)5 are excluded, the AAD improves to 0.3(2) eV. Many other hybrid functionals perform almost as well.

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Section: Resultsmentioning

confidence: 99%

Density functional study of double ionization energies

Chong

2008

The Journal of Chemical Physics

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“…In the present study, we generally applied the LCgau-core appraoch with the BOP exchange-correlation functional. In addition, Chong et al , suggested that the combination of the Perdew–Wang 1986 exchange and the Perdew–Wang 1991 correlation (PW86–PW91) would yield a highly accurate IP and CEBE by taking the difference in the electronic energies of the cationic and neutral species (i.e., the Δ E approach); as a result, we also used the PW86–PW91 functional. The performance of our Koopmans’ approach is studied for a benchmark set of simple molecules (H 2 O, CO, N 2 , HF, H 2 CO, and C 2 H 4 ) and benzene and a set of larger molecules cyclo-C 4 H 4 X with X = CH 2 , NH, O, and S, as well as pyridine.…”

Section: Methodsmentioning

confidence: 99%

Koopmans’-Type Theorem in Kohn–Sham Theory with Optimally Tuned Long-Range-Corrected (LC) Functionals

et al. 2021

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In the present study, we have investigated the applicability of long-range-corrected (LC) functionals to a Kohn–Sham (KS) Koopmans’-type theorem. Specifically, we have examined the performance of optimally tuned LCgau-core functionals (in combination with BOP and PW86-PW91 exchange-correlation functionals) by calculating the ionization potential (IP) within the context of Koopmans’ prediction. In the LC scheme, the electron repulsion operator, 1/r 12, is divided into short-range and long-range components using a standard error function, with a range separation parameter μ determining the weight of the two ranges. For each system that we have examined (H2O, CO, benzene, N2, HF, H2CO, C2H4, and five-membered ring compounds cyclo-C4H4X, with X = CH2, NH, O, and S, and pyridine), the value of μ is optimized to minimize the deviation of the negative HOMO energy from the experimental IP. Our results demonstrate the utility of optimally tuned LC functionals in predicting the IP of outer valence levels. The accuracy is comparable to that of highly accurate ab initio theory. However, our Koopmans’ method is less accurate for the inner valence and core levels. Overall, our results support the notion that orbitals in KS-DFT, when obtained with the LC functional, provide an accurate one-electron energy spectrum. This method represents a one-electron orbital theory that is attractive in its simple formulation and effective in its practical application.

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“…Now we turn our attention to low-lying single-particle levels. In Figure , we compare not only the HOMO but lower-lying single-particle levels with respect to experimental values, summarized in ref . (The ME and MAE between IEs obtained with CCDS(T) and the experimental IEs reported in ref are 0.004 and 0.08 eV, respectively.…”

Section: Resultsmentioning

confidence: 98%

The LDA-1/2 Method Applied to Atoms and Molecules

Pelá

Guļāns

Draxl

2018

J. Chem. Theory Comput.

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The LDA-1/2 method evaluates ionization potentials as the energy of the highest occupied molecular orbitals (HOMOs) at half occupation. It has proven to be a viable approach for calculating band gaps of semiconductors. To address its accuracy for finite systems, we apply LDA-1/2 to the atoms and molecules of the GW100 test set. The obtained HOMO energies are validated against CCSD(T) data and the G W approach of many-body perturbation theory. The accuracy of LDA-1/2 and G W is found to be the same, where the latter is computationally much more involved. To get insight into the benefits and limitations of the LDA-1/2 method, we analyze the impact of each assumption made in deriving the methodology.

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PW86-PW91 density functional calculation of vertical ionization potentials: Some implications for present-day functionals

Cited by 27 publications

References 41 publications

Density functional study of double ionization energies

Density functional study of double ionization energies

Koopmans’-Type Theorem in Kohn–Sham Theory with Optimally Tuned Long-Range-Corrected (LC) Functionals

The LDA-1/2 Method Applied to Atoms and Molecules

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