On the role of dynamic electron correlation in non-orthogonal configuration interaction with fragments

A. Sánchez-Mansilla, C. Sousa*, R. K. Kathir, R. Broer, T. P. Straatsma, C. de Graaf*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Two different approaches have been implemented to include the effect of dynamic electron correlation in the Non-Orthogonal Configuration Interaction for Fragments (NOCI-F) method. The first is based on shifting the diagonal matrix elements of the NOCI matrix, while the second incorporates the dynamic correlation explicitly in the fragment wave functions used to construct the many-electron basis functions of the NOCI. The two approaches are illustrated for the calculation of the electronic coupling relevant in singlet fission and the coupling of spin moments in organic radicals. Comparison of the calculated diabatic couplings, the NOCI energies and wave functions shows that dynamic electron correlation is not only efficiently but also effectively incorporated by the shifting approach and can largely affect the coupling between electronic states. Also, it brings the NOCI coupling of the spin moments in close agreement with benchmark calculations.

Original languageEnglish
Pages (from-to)11931-11944
Number of pages14
JournalPhysical Chemistry Chemical Physics
Volume24
Issue number19
DOIs
Publication statusPublished - 2-May-2022

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