Quantum Chemistry and EPR Parameters

Neese, Frank

doi:10.1002/9780470034590.emrstm1505

Cited by 46 publications

(54 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…DFT methods has proven useful and fairly accurate for calculations of EPR parameters of lighter radicals. 54 Timedomain DFT approaches have had acceptable agreement with absorption spectroscopy and assignments of isolated transitions. However, much work is needed for the computation of heavy main-group radical EPR parameters.…”

Section: Future Outlookmentioning

confidence: 99%

“…Larger disagreement between experiment and predicted hyperfine couplings are observed, including large a iso errors. 54 As the hyperfine coupling is an electronic core property, it is critical that allelectron basis sets are used and the recent development of relativistic contracted basis sets for the employment with relativistic approximation of heavier elements has shown potential to improve the accuracy of calculated EPR properties. 55 In the future, as more stable heavy main-group radicals are isolated, both EPR and its advanced techniques will continue to shed light on the electronic structure of the radical centre.…”

Section: Future Outlookmentioning

confidence: 99%

See 1 more Smart Citation

Applications of electron paramagnetic resonance spectroscopy to heavy main-group radicals

Cutsail

2020

Dalton Trans.

View full text Add to dashboard Cite

show abstract

Section: Future Outlookmentioning

confidence: 99%

Section: Future Outlookmentioning

confidence: 99%

Applications of electron paramagnetic resonance spectroscopy to heavy main-group radicals

Cutsail

2020

Dalton Trans.

View full text Add to dashboard Cite

show abstract

“…Finally, some authors have used DFT calculations to augment their interpretations of EPR data (Bissaro et al, 2018). While useful in a broad context, there are well-known problems in using DFT to give accurate representations of spin Hamiltonian parameters (Neese, 2009(Neese, , 2017. Indeed, these problems appear to be evident in DFT calculations performed on LPMOs.…”

Section: Simulation Proceduresmentioning

confidence: 99%

Production and spectroscopic characterization of lytic polysaccharide monooxygenases

Hemsworth

Ciano

Davies

et al. 2018

Enzymes of Energy Technology

View full text Add to dashboard Cite

Lytic Polysaccharide Monooxygenases (LPMOs, also known as PMOs) are a recently discovered family of enzymes that play a key role in the breakdown of polysaccharide substrates. The ability of LPMOs to introduce chain breaks, using an oxidative mechanism, has particularly attracted attention as the world seeks more cost-effective and environmentally friendly ways of producing second generation biofuels for the future. LPMOs are mononuclear copper dependent enzymes and have an unusual active site which includes the N-terminal residue of the protein in the copper coordination sphere. This N-terminal histidine sidechain is also methylated in fungal enzymes, the molecular reason for which is still a debated topic. The production of these enzymes poses several challenges if we are to understand their chemical mechanisms. Here we describe the methods that have been used in the field to produce LPMOs and provide information on the workflows that we use for our Electron Paramagnetic Resonance (EPR) Spectroscopy experiments. EPR has been a particularly powerful tool in the study of these enzymes and our objective with this chapter is to provide some helpful information for researchers for whom this technique might be daunting or theoretically difficult to access.

show abstract

“… 26 Furthermore, a nonrigorous motivation for the validity of eq 14 for the full A and g tensors was given by Autschbach et al 43 The FC contribution to A vanishes in the long-distance limit, where there should be no spin density at the position of the nucleus. At the level of second-order degenerate perturbation theory (DPT2), the remaining contributions to g and A are 36 , 44 − 46 where the |Ψ I SS ⟩ are the principal components ( M = S ) of the eigenstates of the nonrelativistic zeroth-order Hamiltonian H 0 nonrel = H 0 – H SOC with eigenvalues E I (0),nonrel . Equations 16 and 18 are the well-known orbital contributions to g and A , which make sizable contributions for transition metals, where SOC cannot be neglected.…”

mentioning

confidence: 99%

Solution of a Puzzle: High-Level Quantum-Chemical Treatment of Pseudocontact Chemical Shifts Confirms Classic Semiempirical Theory

Lang

Ravera

Parigi

et al. 2020

J. Phys. Chem. Lett.

Self Cite

View full text Add to dashboard Cite

A recently popularized approach for the calculation of pseudocontact shifts (PCSs) based on first-principles quantum chemistry (QC) leads to different results than the classic “semiempirical” equation involving the susceptibility tensor. Studies that attempted a comparison of theory and experiment led to conflicting conclusions with respect to the preferred theoretical approach. In this Letter, we show that after inclusion of previously neglected terms in the full Hamiltonian, one can deduce the semiempirical equations from a rigorous QC-based treatment. It also turns out that in the long-distance limit, one can approximate the complete A tensor in terms of the g tensor. By means of Kohn–Sham density functional theory calculations, we numerically confirm the long-distance expression for the A tensor and the theoretically predicted scaling behavior of the different terms. Our derivation suggests a computational strategy in which one calculates the susceptibility tensor and inserts it into the classic equation for the PCS.

show abstract

Quantum Chemistry and EPR Parameters

Cited by 46 publications

References 66 publications

Applications of electron paramagnetic resonance spectroscopy to heavy main-group radicals

Applications of electron paramagnetic resonance spectroscopy to heavy main-group radicals

Production and spectroscopic characterization of lytic polysaccharide monooxygenases

Solution of a Puzzle: High-Level Quantum-Chemical Treatment of Pseudocontact Chemical Shifts Confirms Classic Semiempirical Theory

Contact Info

Product

Resources

About