Combining Multiconfiguration and Perturbation Methods: Perturbative Estimates of Core–Core Electron Correlation Contributions to Excitation Energies in Mg-Like Iron

UBC Faculty Research and Publications

Combining Multiconfiguration and Perturbation Methods: Perturbative Estimates of Core–Core Electron Correlation Contributions to Excitation Energies in Mg-Like Iron Gustafsson, Stefan; Jönsson, Per; Froese Fischer, Charlotte; Grant, Ian

Abstract

Large configuration interaction (CI) calculations can be performed if part of the interaction is treated perturbatively. To evaluate the combined CI and perturbative method, we compute excitation energies for the 3l3l', 3l4l' and 3s5l states in Mg-like iron. Starting from a CI calculation including valence and core–valence correlation effects, it is found that the perturbative inclusion of core–core electron correlation halves the mean relative differences between calculated and observed excitation energies. The effect of the core–core electron correlation is largest for the more excited states. The final relative differences between calculated and observed excitation energies is 0.023%, which is small enough for the calculated energies to be of direct use in line identifications in astrophysical and laboratory spectra.

Item Metadata

Title	Combining Multiconfiguration and Perturbation Methods: Perturbative Estimates of Core–Core Electron Correlation Contributions to Excitation Energies in Mg-Like Iron
Creator	Gustafsson, Stefan; Jönsson, Per; Froese Fischer, Charlotte; Grant, Ian
Publisher	Multidisciplinary Digital Publishing Institute
Date Issued	2017-01-12
Description	Large configuration interaction (CI) calculations can be performed if part of the interaction is treated perturbatively. To evaluate the combined CI and perturbative method, we compute excitation energies for the 3l3l', 3l4l' and 3s5l states in Mg-like iron. Starting from a CI calculation including valence and core–valence correlation effects, it is found that the perturbative inclusion of core–core electron correlation halves the mean relative differences between calculated and observed excitation energies. The effect of the core–core electron correlation is largest for the more excited states. The final relative differences between calculated and observed excitation energies is 0.023%, which is small enough for the calculated energies to be of direct use in line identifications in astrophysical and laboratory spectra.
Subject	Excitation energies; Multiconfiguration Dirac–Hartree–Fock; Configuration interaction
Genre	Article
Type	Text
Language	eng
Date Available	2019-05-29
Provider	Vancouver : University of British Columbia Library
Rights	CC BY 4.0
DOI	10.14288/1.0379159
URI	http://hdl.handle.net/2429/70390
Affiliation	Applied Science, Faculty of; Non UBC; Computer Science, Department of
Citation	Atoms 5 (1): 3 (2017)
Publisher DOI	10.3390/atoms5010003
Peer Review Status	Reviewed
Scholarly Level	Faculty
Rights URI	https://creativecommons.org/licenses/by/4.0/
Aggregated Source Repository	DSpace

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