Relativistic Methods for Calculating Electron Paramagnetic Resonance (EPR) Parameters

Bolvin, Hélène; Autschbach, Jochen

doi:10.1007/978-3-642-41611-8_12-1

Cited by 6 publications

(16 citation statements)

References 51 publications

(58 reference statements)

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“…Then, D describes the splitting induced by second-order spin-orbit and first order spin-spin coupling and may be computed using perturbation theory arguments. 3,33,34,44 However, in some cases such a low-rank analysis can be performed anyways, and the spectrum of H ZFS , may serve as a marker for assessing the validity of the model.…”

Section: Quantum Chemical Calculationsmentioning

confidence: 99%

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Magnetic anisotropy in trigonal planar Fe(ii) bis(trimethylsilyl)amido complexes of the type [Fe{N(SiMe₃)₂}₂L]—experiment and theory

Bodenstein

Eichhöfer

2019

Dalton Trans.

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Section: Quantum Chemical Calculationsmentioning

confidence: 99%

“…In this case, a model featuring higher-rank spin operators might improve the accuracy of the values, but not the validity of the S = 2 pseudo spin description for type A complexes in the first place. 34 For the computation of magnetic susceptibilities, all 210 microstates where considered in the Boltzmann-averaging.…”

Section: Quantum Chemical Calculationsmentioning

confidence: 99%

Magnetic anisotropy in trigonal planar Fe(ii) bis(trimethylsilyl)amido complexes of the type [Fe{N(SiMe₃)₂}₂L]—experiment and theory

Bodenstein

Eichhöfer

2019

Dalton Trans.

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“…The methodology used in this work was presented in detail in Refs. [28,[31][32]. Thus, here we briefly explain only the key points and specifics for the 161 DyPc 2 and 163 DyPc 2 SMMs.…”

Section: Methodology and Computational Detailsmentioning

confidence: 99%

Hyperfine and quadrupole interactions for Dy isotopes in DyPc₂ molecules

Wysocki

Park

2020

J. Phys.: Condens. Matter

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Nuclear spin levels play an important role in understanding magnetization dynamics and implementation and control of quantum bits in lanthanide-based singlemolecule magnets. We investigate the hyperfine and nuclear quadrupole interactions for 161 Dy and 163 Dy nucleus in anionic DyPc 2 (Pc=phthalocyanine) single-molecule magnets, using multiconfigurational ab-initio methods (beyond density-functional theory) including spin-orbit interaction. The two isotopes of Dy are chosen because the others have zero nuclear spin. Both isotopes have the nuclear spin I = 5/2, although the magnitude and sign of the nuclear magnetic moment differ from each other. The large energy gap between the electronic ground and first-excited Kramers doublets, allows us to map the microscopic hyperfine and quadrupole interaction Hamiltonian onto an effective Hamiltonian with an electronic pseudo-spin S eff = 1/2 that corresponds to the ground Kramers doublet. Our ab-initio calculations show that the coupling between the nuclear spin and electronic orbital angular momentum contributes the most to the hyperfine interaction and that both the hyperfine and nuclear quadrupole interactions for 161 Dy and 163 Dy nucleus are much smaller than those for 159 Tb nucleus in TbPc 2 single-molecule magnets. The calculated separations of the electronic-nuclear levels are comparable to experimental data reported for 163 DyPc 2 . We demonstrate that hyperfine interaction for Dy Kramers ion leads to tunnel splitting (or quantum tunneling of magnetization) at zero field. This effect does not occur for TbPc 2 single-molecule magnets. The magnetic field values of the avoided level crossings for 161 DyPc 2 and 163 DyPc 2 are found to be noticeably different, which can be observed from experiment.

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“…In the absence of spin-orbit coupling S = S, which is an often-used approximation. For molecules where the spin-orbit interaction is strong, the effective degeneracy of the molecule is reduced so a smaller effective spin S is chosen based on the splitting pattern of the electronic states [17]. The interaction between the nuclear and electronic spin-dipoles is represented by the hyperfine coupling matrix, A.…”

Section: The Spin Hamiltonian Approach To Paramagnetic Nmrmentioning

confidence: 99%

“…To achieve reliable results it is necessary to assess each component, and calibrate the most effective approach against an often-limited set of experimental values for similar chemical species. Detailed overviews of the evaluation of spin Hamiltonian parameters in the context of modern computational chemistry are available from Vaara [16], Bolvin [17] and Autschbach [18]. We shall mostly be concerned with studying the effect of zero field splitting (ZFS) on the predicted 1 H, 13 C, 29 Si shifts of six compounds.…”

Section: Introductionmentioning

confidence: 99%

Modelling the Effect of Zero-Field Splitting on the 1H, 13C and 29Si Chemical Shifts of Lanthanide and Actinide Compounds

2019

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The prediction of paramagnetic NMR (pNMR) chemical shifts in molecules containing heavy atoms presents a significant challenge to computational quantum chemistry. The importance of meeting this challenge lies in the central role that NMR plays in the structural characterisation of chemical systems. Hence there is a need for reliable assignment and prediction of chemical shifts. In a previous study [Trends in Physical Chemistry, 17, 25–57, (2017)] we looked at the computation of pNMR chemical shifts in lanthanide and actinide complexes using a spin Hamiltonian approach. In that study we were principally concerned with molecules with S = 1/2 ground states. In the present work we extend that study by looking at the effect of zero field splitting (ZFS) for six complexes with S = 3/2 ground states. It is shown that the inclusion of ZFS can produce substantial shifts in the predicted chemical shifts. The computations presented are typically sufficient to enable assignment of experimental spectra. However for one case, in which the peaks are closely clustered, the inclusion of ZFS re-orders the chemical shifts making assignment quite difficult. We also observe, and echo, the previously reported importance of including the paramagnetic spin-orbit hyperfine interaction for 13 C and 29 Si atoms, when these are directly bound to a heavy element and thus subject to heavy-atom-light-atom effects. The necessary computations are very demanding, and more work is needed to find theoretical and computational approaches that simplify the evaluation of this term. We discuss the computation of each term required in the spin Hamiltonian. The systems we study in this work are restricted to a single heavy atom ion (one Nd(III) and five U(III) complexes), but typify some of the computational complexity encountered in lanthanide and actinide containing molecules.

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Relativistic Methods for Calculating Electron Paramagnetic Resonance (EPR) Parameters

Cited by 6 publications

References 51 publications

Magnetic anisotropy in trigonal planar Fe(ii) bis(trimethylsilyl)amido complexes of the type [Fe{N(SiMe₃)₂}₂L]—experiment and theory

Magnetic anisotropy in trigonal planar Fe(ii) bis(trimethylsilyl)amido complexes of the type [Fe{N(SiMe₃)₂}₂L]—experiment and theory

Hyperfine and quadrupole interactions for Dy isotopes in DyPc₂ molecules

Modelling the Effect of Zero-Field Splitting on the 1H, 13C and 29Si Chemical Shifts of Lanthanide and Actinide Compounds

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Relativistic Methods for Calculating Electron Paramagnetic Resonance (EPR) Parameters

Cited by 6 publications

References 51 publications

Magnetic anisotropy in trigonal planar Fe(ii) bis(trimethylsilyl)amido complexes of the type [Fe{N(SiMe3)2}2L]—experiment and theory

Magnetic anisotropy in trigonal planar Fe(ii) bis(trimethylsilyl)amido complexes of the type [Fe{N(SiMe3)2}2L]—experiment and theory

Hyperfine and quadrupole interactions for Dy isotopes in DyPc2 molecules

Modelling the Effect of Zero-Field Splitting on the 1H, 13C and 29Si Chemical Shifts of Lanthanide and Actinide Compounds

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Magnetic anisotropy in trigonal planar Fe(ii) bis(trimethylsilyl)amido complexes of the type [Fe{N(SiMe₃)₂}₂L]—experiment and theory

Magnetic anisotropy in trigonal planar Fe(ii) bis(trimethylsilyl)amido complexes of the type [Fe{N(SiMe₃)₂}₂L]—experiment and theory

Hyperfine and quadrupole interactions for Dy isotopes in DyPc₂ molecules