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A scaled CIS(D) based method for the calculation of valence and core electron ionization energies

Hanson-Heine, Magnus W. D.; George, Michael W.; Besley, Nicholas A.


Magnus W. D. Hanson-Heine

Michael W. George

Nicholas A. Besley


The calculation of electron ionisation energies is a key component for the simulation of photoelectron spectroscopy. CIS(D) is a perturbative doubles correction for the single excitation configuration interaction (CIS) method which provides a new approach for computing excitation energies. It is shown that by introducing a virtual orbital subspace that consistsofasingle’ghost’orbital,valenceelectronionisationenergiescanbecomputedusingascaledCIS(D)approach with an accuracy comparable with considerably more computationally intensive methods, such as ionisation-potential equationofmotioncoupledclustertheory(EOM-IP-CCSD),andsimulatedspectrashowasignificantimprovementrelative to spectra based upon Koopmans’ theorem. When the model is applied to the ionisation energies for core orbitals thereis anincrease intheerror, particularlyfor theheavier nucleiconsidered (siliconto chlorine), althoughthe relative energy of the ionisation energies are predicted accurately. In addition to its inherent computational efficiency relative to other wavefunction based approaches, a significant advantage of this approach is that the ionisation energies for all electrons can be obtained in a single calculation, in contrast to∆self-consistent field based methods.

Journal Article Type Article
Publication Date Jul 21, 2019
Journal The Journal of Chemical Physics
Print ISSN 0021-9606
Electronic ISSN 1089-7690
Publisher AIP Publishing
Peer Reviewed Peer Reviewed
Volume 151
Issue 3
Article Number 034104
APA6 Citation Hanson-Heine, M. W. D., George, M. W., & Besley, N. A. (2019). A scaled CIS(D) based method for the calculation of valence and core electron ionization energies. Journal of Chemical Physics, 151(3), doi:10.1063/1.5100098
Keywords Physical and Theoretical Chemistry; General Physics and Astronomy
Publisher URL
Additional Information This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Chem. Phys. 151, 034104 (2019) and may be found at (


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