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Core ionization potentials from self-interaction corrected Kohn-Sham Orbital energies
KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).ORCID iD: 0000-0002-9123-8174
KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).ORCID iD: 0000-0002-1763-9383
2007 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 127, no 17, 174110- p.Article in journal (Refereed) Published
Abstract [en]

We propose a simple self-interaction correction to Kohn-Sham orbital energies in order to apply ground state Kohn-Sham density functional theory to accurate predictions of core electron binding energies and chemical shifts. The proposition is explored through a series of calculations of organic compounds of different sizes and types. Comparison is made versus experiment and the " ΔKohn -Sham" method employing separate state optimizations of the ground and core hole states, with the use of the B3LYP functional and different basis sets. A parameter α is introduced for a best fitting of computed and experimental ionization potentials. It is found that internal parametrizations in terms of basis set expansions can be well controlled. With a unique α=0.72 and basis set larger than 6-31G, the core ionization energies (IPs) of the self-interaction corrected Kohn-Sham calculations fit quite well to the experimental values. Hence, self-interaction corrected Kohn-Sham calculations seem to provide a promising tool for core IPs that combines accuracy and efficiency.

Place, publisher, year, edition, pages
2007. Vol. 127, no 17, 174110- p.
Keyword [en]
Binding energy, Chemical shift, Density functional theory, Electrons, Organic compounds
National Category
Theoretical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-8409DOI: 10.1063/1.2777141ISI: 000250787300012Scopus ID: 2-s2.0-35948963605OAI: oai:DiVA.org:kth-8409DiVA: diva2:13721
Note
QC 20100906. Previous title: Self-interaction correction to Kohn-Sham core orbital energies in molecules.Available from: 2008-05-09 Created: 2008-05-09 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Studies of Self-interaction Corrections in Density Functional Theory
Open this publication in new window or tab >>Studies of Self-interaction Corrections in Density Functional Theory
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The self-interaction error (SIE) in density functional theory (DFT) appears from the fact that the residual self-interaction in the Coulomb part and that in the exchange part do not cancel each other exactly. This error is responsible for the unphysical orbital energies of DFT and the failure to reproduce the potential energy curves of several physical processes.

The present thesis addresses several methods to solve the problem of SIE in DFT. A new algorithm is presented which is based on the Perdew-Zunger (PZ) energy correction and which includes the self-interaction correction (SIC) self-consistently (SC SIC PZ).

When applied to the study of hydrogen abstraction reactions, for which conventional DFT can not describe the processes properly, SC PZ SIC DFT produces reasonable potential energy curves along the reaction coordinate and reasonable transition barriers.

A semi-empirical SIC method is designed to correct the orbital energies. It is found that a potential coupling term is generally nonzero for all available approximate functionals. This coupling term also contributes to the self-interaction error. In this scheme, the potential coupling term is multiplied by an empirical parameter , introduced to indicate the strength of the potential coupling, and used to correct the PZ SIC DFT. Through a fitting scheme, we find that a unique can be used for C, N, O core orbitals in different molecules. Therefore this method is now used to correct the core orbital energies and relevant properties. This method is both efficient and accurate in predicting core ionization energies.

A new approach has been designed to solve the problem of SIE. A functional is constructed based on electron-electron interactions, Coulomb and exchange-correlation parts, which are free of SIE. A post-SCF procedure for this method has been implemented. The orbital energies thus obtained are of higher quality than in conventional DFT. For a molecular system, the orbital energy of the highest occupied molecular orbital (HOMO) is comparable to the experimental first ionization potential energy.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. 51 p.
Series
Trita-BIO-Report, ISSN 1654-2312 ; 2008:11
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-4740 (URN)978-91-7178-964-8 (ISBN)
Public defence
2008-05-28, FB52, AlbaNova, Roslagstullsbacken, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100915Available from: 2008-05-09 Created: 2008-05-09 Last updated: 2010-09-15Bibliographically approved
2. Studies of self-interaction corrections in density functional theory
Open this publication in new window or tab >>Studies of self-interaction corrections in density functional theory
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Place, publisher, year, edition, pages
Stockholm: KTH, 2007. v, 27 p.
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-4450 (URN)978-91-7178-648-7 (ISBN)
Presentation
2007-05-24, FD41, KTH, AlbaNova, Stockholm, 11:00
Opponent
Supervisors
Note
QC 20101119Available from: 2007-06-20 Created: 2007-06-20 Last updated: 2011-09-02Bibliographically approved

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Vahtras, OlavÅgren, Hans

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