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How Much Dispersion Energy Is Included in the Multiconfigurational Interaction Energy?

ABSTRACT: We demonstrate how to quantify the amount of dispersion interaction recovered by supermolecular calculations with the multiconfigurational self-consistent field (MCSCF) wave functions. For this purpose, we present a rigorous derivation which connects the portion of dispersion interaction captured by the assumed wave function model-the residual dispersion interaction-with the size of the active space. Based on the obtained expression for the residual dispersion contribution, we propose a dispersion correction for the MCSCF that avoids correlation double counting. Numerical demonstration for model four-electron dimers in both ground and excited states described with the complete active space self-consistent field (CASSCF) reference serves as a proof-of-concept for the method. Accurate results, largely independent of the size of the active space, are obtained. For many-electron systems, routine CASSCF interaction energy calculations recover a tiny fraction of the full second-order dispersion energy. We found that the residual dispersion is non-negligible only for purely dispersion-bound complexes.

SUBMITTER: Hapka M

PROVIDER: S-EPMC7586340 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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How Much Dispersion Energy Is Included in the Multiconfigurational Interaction Energy?

Hapka Michał M Krzemińska Agnieszka A Pernal Katarzyna K

Journal of chemical theory and computation 20200918 10

We demonstrate how to quantify the amount of dispersion interaction recovered by supermolecular calculations with the multiconfigurational self-consistent field (MCSCF) wave functions. For this purpose, we present a rigorous derivation which connects the portion of dispersion interaction captured by the assumed wave function model-the residual dispersion interaction-with the size of the active space. Based on the obtained expression for the residual dispersion contribution, we propose a dispersi ...[more]

PMID: 32877179

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How Much Dispersion Energy Is Included in the Multiconfigurational Interaction Energy?

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How Much Dispersion Energy Is Included in the Multiconfigurational Interaction Energy?

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