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Computation of Molecular Electron Affinities Using an Ensemble Density Functional Theory Method

Filatov, Michael and Lee, Seunghoon and Nakata, Hiroya and Choi, Cheol Ho (2020) Computation of Molecular Electron Affinities Using an Ensemble Density Functional Theory Method. Journal of Physical Chemistry A, 124 (38). pp. 7795-7804. ISSN 1089-5639. doi:10.1021/acs.jpca.0c06976.

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The computation of electron attachment energies (electron affinities) was implemented in connection with an ensemble density functional theory method, the state-interaction state-averaged spin-restricted ensemble-referenced Kohn–Sham (SI-SA-REKS or SSR) method. With the use of the extended Koopmans’ theorem, the electron affinities and the respective Dyson orbitals are obtained directly for the neutral molecule, thus avoiding the necessity to compute the ionized system. Together with the EKT-SSR (extended Koopmans’ theorem-SSR) method for ionization potentials, which was developed earlier, EKT-SSR for electron affinities completes the implementation of the EKT-SSR formalism, which can now be used for obtaining electron detachment as well as the electron attachment energies of molecules in the ground and excited electronic states. The extended EKT-SSR method was tested in the calculation of several closed-shell molecules. For the molecules in the ground states, the EKT-SSR energies of Dyson’s orbitals are virtually identical to the energies of the unoccupied orbitals in the usual single-reference spin-restricted Kohn–Sham calculations. For the molecules in the excited states, EKT-SSR predicts an increase of the most positive electron affinity by approximately the amount of the vertical excitation energy. The electron affinities of a number of diradicals were calculated with EKT-SSR and compared with the available experimental data. With the use of a standard density functional (BH&HLYP), the EKT-SSR electron affinities deviate on average by ca. 0.2 eV from the experimental data. It is expected that the agreement with the experiment can be improved by designing density functionals parametrized for ionization energies.

Item Type:Article
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URLURL TypeDescription
Filatov, Michael0000-0002-1541-739X
Choi, Cheol Ho0000-0002-8757-1396
Additional Information:© 2020 American Chemical Society. Received: July 30, 2020; Revised: September 8, 2020; Published: September 8, 2020. This work was supported by the National Research Foundation of Korea (NRF) grant 2019H1D3A2A02102948. The authors declare no competing financial interest.
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National Research Foundation of Korea2019H1D3A2A02102948
Issue or Number:38
Record Number:CaltechAUTHORS:20200911-133137506
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Official Citation:Computation of Molecular Electron Affinities Using an Ensemble Density Functional Theory Method. Michael Filatov, Seunghoon Lee, Hiroya Nakata, and Cheol Ho Choi. The Journal of Physical Chemistry A 2020 124 (38), 7795-7804; DOI: 10.1021/acs.jpca.0c06976
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105349
Deposited By: George Porter
Deposited On:14 Sep 2020 14:03
Last Modified:16 Nov 2021 18:42

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