In this paper, we have extended to the calculation of hyperfine coupling constants, the model recently proposed by some of the present authors [Giovannini et al., J. Chem. Theory Comput. 13, 4854-4870 (2017)] to include Pauli repulsion and dispersion effects in Quantum Mechanical/Molecular Mechanics (QM/MM) approaches. The peculiarity of the proposed approach stands in the fact that repulsion/dispersion contributions are explicitly introduced in the QM Hamiltonian. Therefore, such terms not only enter the evaluation of energetic properties but also propagate to molecular properties and spectra. A novel parametrization of the electrostatic fluctuating charge force field has been developed, thus allowing a quantitative reproduction of reference QM interaction energies. Such a parametrization has been then tested against the prediction of EPR parameters of prototypical nitroxide radicals in aqueous solutions.
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http://dx.doi.org/10.1063/1.5080810 | DOI Listing |
Chemphyschem
December 2024
Oxford University, Department of Chemistry, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND.
With a view towards the development of molecular spintronics, non-linear optics, and qubits, a great amount of research effort aims to establish the factors which govern the spin classification of diradicals. Electron spin resonance (ESR) is an indispensable tool for such research. However, in some cases, the mere presence of an ESR spectrum is insufficient to ascertain that the presumed diradical is indeed a triplet state.
View Article and Find Full Text PDFJ Chem Theory Comput
December 2024
Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany.
Density functional theory has become the workhorse of quantum physics, chemistry, and materials science. Within these fields, a broad range of applications needs to be covered. These applications range from solids to molecular systems, from organic to inorganic chemistry, or even from electrons to other Fermions, such as protons or muons.
View Article and Find Full Text PDFSci Rep
December 2024
Semiconductor Physics, Institute of Physics, Chemnitz University of Technology, 09126, Chemnitz, Germany.
Magnetic field effects (MFEs) in thermally activated delayed fluorescence (TADF) materials have been shown to influence the reverse intersystem crossing (RISC) and to impact on electroluminescence (EL) and conductivity. Here, we present a novel model combining Cole-Cole and Lorentzian functions to describe low and high magnetic field effects originating from hyperfine coupling, the Δg mechanism, and triplet processes. We applied this approach to organic light-emitting devices of third generation based on tris(4-carbazoyl-9-ylphenyl)amine (TCTA) and 2,2',2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), exhibiting blue emission, to unravel their loss mechanisms.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Chemistry "U. Schiff", University of Florence & UdR INSTM Firenze, 50019 Sesto Fiorentino, Italy.
Photoexcited organic chromophores appended to molecular qubits can serve as a source of spin initialization or multilevel qudit generation for quantum information applications. So far, this approach has been primarily investigated in chromophore-stable radical systems. Here, we extend this concept to a linked oxovanadium(IV) porphyrin-free-base porphyrin dimer.
View Article and Find Full Text PDFPhys Rev Lett
November 2024
Center for Theoretical Physics & School of Physics and Optoelectronic Engineering, Hainan University, Haikou 570228, China.
The electronic bridge (EB) excitation of nuclei has been found as a versatile approach to efficiently excite the ^{229}Th isomers. Previous studies on EB excitation have typically disregarded the hyperfine structure as well as the decay of the excited atoms and ions by just treating the nucleus-electron coupling perturbatively. In the present work, we apply a quantum-optical approach to nonperturbatively investigate EB excitation of ^{229}Th^{3+} ions.
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