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Role of Spin Polarization and Dynamic Correlation in Singlet–Triplet Gap Inversion of Heptazine Derivatives
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SYSNO ASEP 0576888 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Role of Spin Polarization and Dynamic Correlation in Singlet–Triplet Gap Inversion of Heptazine Derivatives Author(s) Drwal, D. (PL)
Matoušek, Mikuláš (UFCH-W)
Golub, Pavlo (UFCH-W) ORCID, RID, SAI
Tucholska, A. (PL)
Hapka, M. (PL)
Brabec, Jiří (UFCH-W) RID, ORCID
Veis, Libor (UFCH-W) RID, ORCID
Pernal, K. (PL)Source Title Journal of Chemical Theory and Computation . - : American Chemical Society - ISSN 1549-9618
Roč. 19, č. 21 (2023), s. 7606-7616Number of pages 11 s. Language eng - English Country US - United States Keywords Energy ; Determinants ; Quantum mechanics Subject RIV CF - Physical ; Theoretical Chemistry OECD category Physical chemistry R&D Projects GF23-04302L GA ČR - Czech Science Foundation (CSF) Research Infrastructure e-INFRA CZ II - 90254 - CESNET, zájmové sdružení právnických osob Method of publishing Open access Institutional support UFCH-W - RVO:61388955 UT WOS 001105081900001 EID SCOPUS 85176140728 DOI https://doi.org/10.1021/acs.jctc.3c00781 Annotation The new generation of proposed light-emitting molecules for organic light-emitting diodes (OLEDs) has raised considerable research interest due to its exceptional feature─a negative singlet–triplet (ST) gap violating Hund’s multiplicity rule in the excited S1 and T1 states. We investigate the role of spin polarization in the mechanism of ST gap inversion. Spin polarization is associated with doubly excited determinants of certain types, whose presence in the wave function expansion favors the energy of the singlet state more than that of the triplet. Using a perturbation theory-based model for spin polarization, we propose a simple descriptor for prescreening of candidate molecules with negative ST gaps and prove its usefulness for heptazine-type molecules. Numerical results show that the quantitative effect of spin polarization decreases linearly with the increasing highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) exchange integral. Comparison of single- and multireference coupled-cluster predictions of ST gaps shows that the former methods provide good accuracy by correctly balancing the effects of doubly excited determinants and dynamic correlation. We also show that accurate ST gaps may be obtained using a complete active space model supplemented with dynamic correlation from multireference adiabatic connection theory. Workplace J. Heyrovsky Institute of Physical Chemistry Contact Michaela Knapová, michaela.knapova@jh-inst.cas.cz, Tel.: 266 053 196 Year of Publishing 2024 Electronic address https://hdl.handle.net/11104/0346286
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