Anomalous values of 〈Ŝ2〉 before and after annihilation of the first spin contaminant in UHF wave function

Plakhutin, B. N.; Gorelik, E. V.; Breslavskaya, N. N.; Milov, M. A.; Fokeyev, Anatoly A.; Новиков, А. В.; Prokhorov, T. E.; Polygalova, N. E.; Dolin, S. P.; Трахтенберг, Л. И.

doi:10.1007/s10947-006-0031-3

Cited by 5 publications

(6 citation statements)

References 9 publications

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“…The UBLYP functional and 6-31G(d) basis set are necessary since when calculating J values with the UB3LYP functional and 6-31G(d) basis set, it is well-known that the overestimation of J intra ( calc ) occurs due to the spin contamination from Hartree–Fock contributions . This was also found here (Table S3).…”

Section: Resultssupporting

confidence: 75%

“…41,45 The UBLYP functional and 6-31G(d) basis set are necessary since when calculating J values with the UB3LYP functional and 6-31G(d) basis set, it is well-known that the overestimation of J intra (calc) occurs due to the spin contamination from Hartree− Fock contributions. 60 This was also found here (Table S3). The theoretical exchange interaction of the TTT-NN was studied previously with the UB3LYP functional, 61 leading to stronger exchange than that with BLYP functional.…”

Section: The Journal Of Organic Chemistrysupporting

confidence: 85%

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Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

et al. 2017

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The synthesis of four nitronyl nitroxide (NN) biradicals is described which are conjugatively linked through p-ter-phenyl (PPP), ter-thiophene (TTT) and alternating phenylene (P) and thiophene (T) units as PTP and TPT. We first utilized Suzuki and Stille coupling reactions through protection and deprotection protocols to synthesize these (NN) biradicals. Single crystals were efficiently grown for radical precursors of 3, 5, 6, PPP-NNSi, PTP-NNSi, and final biradicals of TTT-NN, TPT-NN, and PPP-NN, whose structures and molecular packing were examined by X-ray diffraction studies. As a result, much smaller torsions between the NN and thiophene units (∼10°) in TTT-NN and TPT-NN than for NN and phenyl units (∼29°) in PPP-NN were observed due to smaller hindrance for a five vs a six membered ring. All four biradicals TTT-NN, TPT-NN, PTP-NN, and PPP-NN were investigated by EPR and optical spectroscopy combined with DFT calculations. The magnetic susceptibility was studied by SQUID measurements for TTT-NN and TPT-NN. The intramolecular exchange interactions for TPT-NN and TTT-NN were found in good agreement with the ones calculated by broken symmetry DFT calculations.

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Section: Resultssupporting

confidence: 75%

Section: The Journal Of Organic Chemistrysupporting

confidence: 85%

Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

et al. 2017

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“…20 The observed overestimation of the calculated J values using the UB3LYP functional can be attributed to the high spin contamination brought by Hartree−Fock. 21 Thus, to avoid the Hartree−Fock spin contamination, we calculated J with the UBLYP functional using the 6-31G(d) basis set. Interestingly, UBLYP/6-31G(d) provided rather accurate results.…”

Section: ■ Dft Calculationsmentioning

confidence: 99%

Crystal Engineering of Tolane Bridged Nitronyl Nitroxide Biradicals: Candidates for Quantum Magnets

Ravat

Borozdina

Ito

et al. 2014

Crystal Growth & Design

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The tolane bridged nitronyl nitroxide biradicals with hydrogen bond donor and acceptor functional groups were synthesized. The magnetic measurements and the DFT calculations were performed to ascertain the influence of the functional groups on inter-and intramolecular magnetic exchange interactions. While upon functionalizing the tolane bridge the intramolecular exchange interactions remained nearly unchanged, the fine-tuning of intermolecular exchange interactions could be achieved by employing the crystal engineering approach.

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“…After annihilation, the spin square is increased, which demonstrates the effect observed earlier on other molecular systems. This effect was discussed earlier by Davidson and Clark and Plakhutin et al and is explained by the fact that the spin state is contaminated by the higher order spin admixtures which are more dominant after the annihilation of the first order spin component. This fact is a consequence of the restricted description of the spin state in the framework of the single-reference wave functions and has no solution up to date within the DFT theory, both for the cluster and periodic models.…”

Section: Resultsmentioning

confidence: 71%

Adsorption and Diffusion of Hydrogen on the Surface of the Pt₂₄ Subnanoparticle. A DFT Study

et al. 2016

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Platinum and platinum based materials are of fundamental importance for modern and developed catalysts, fuel cells, sensors, hydrogen production and storage systems, and nanoelectronic devices. The subnanosize cluster Pt24 was considered as a model of the prospective catalytic system based on the oxide and carbide supported Pt nanoparticles (Pt NPs) or Pt NPs with soft spacers anchored to their surface. Structural, electronic, thermodynamic, and spectral properties of the adsorption complexes of molecular and atomic hydrogen on Pt NPs have been studied using the DFT method (the BLYP functional with the 6-31G(p) basis for H and the CRENBS pseudopotential for Pt atoms). On this basis, the adsorption energies for molecular hydrogen at the Pt NPs along with the energies and activation energies of its dissociation were estimated and the pathways of activationless dissociative adsorption were found. The full map of adsorption energies of atomic hydrogen at the various surface regions of Pt24 was obtained. The structures of transition states for the rearrangements between the adsorption complexes were located, and the activation energies for surface migration were calculated. Additionally, several ways of subsurface diffusion of H atoms inside the Pt24 cluster were considered which allows estimating the diffusion parameters and the probability of the hydrogen spillover when the cluster surface is highly covered by ligands restricting the surface migration. The IR and Raman spectra of most favorable adsorption complexes were simulated to provide the possibility of an experimental validation of the results obtained.

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Anomalous values of 〈Ŝ2〉 before and after annihilation of the first spin contaminant in UHF wave function

Cited by 5 publications

References 9 publications

Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

Crystal Engineering of Tolane Bridged Nitronyl Nitroxide Biradicals: Candidates for Quantum Magnets

Adsorption and Diffusion of Hydrogen on the Surface of the Pt₂₄ Subnanoparticle. A DFT Study

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Anomalous values of 〈Ŝ2〉 before and after annihilation of the first spin contaminant in UHF wave function

Cited by 5 publications

References 9 publications

Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

Mixed Phenyl and Thiophene Oligomers for Bridging Nitronyl Nitroxides

Crystal Engineering of Tolane Bridged Nitronyl Nitroxide Biradicals: Candidates for Quantum Magnets

Adsorption and Diffusion of Hydrogen on the Surface of the Pt24 Subnanoparticle. A DFT Study

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Adsorption and Diffusion of Hydrogen on the Surface of the Pt₂₄ Subnanoparticle. A DFT Study