A multireference perturbation theory study on the Fe<sub>2</sub>molecule: in quest of the ground state

Angeli, Celestino; Cimiraglia, Renzo

doi:10.1080/00268976.2011.566586

Cited by 27 publications

(19 citation statements)

References 40 publications

(67 reference statements)

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“…We shall then present case studies of excited states of different nature, such as valence, ionic, Rydberg, and CT states, in small benchmark organic molecules, using highly correlated Multireference Perturbation Theory methods (NEVPT) developed by some of us [70][71][72][73][74][75] and already successfully applied to the description of the spectroscopic properties of both organic and inorganic molecules. [76][77][78][79][80][81][82] …”

Section: Introductionmentioning

confidence: 99%

Charge-displacement analysis for excited states

Ronca

Pastore

Belpassi

et al. 2014

The Journal of Chemical Physics

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We extend the Charge-Displacement (CD) analysis, already successfully employed to describe the nature of intermolecular interactions [L. Belpassi et al., J. Am. Chem. Soc. 132, 13046 (2010)] and various types of controversial chemical bonds [L. Belpassi et al., J. Am. Chem. Soc. 130, 1048 (2008); N. Salvi et al., Chem. Eur. J. 16, 7231 (2010)], to study the charge fluxes accompanying electron excitations, and in particular the all-important charge-transfer (CT) phenomena. We demonstrate the usefulness of the new approach through applications to exemplary excitations in a series of molecules, encompassing various typical situations from valence, to Rydberg, to CT excitations. The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.

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Section: Introductionmentioning

confidence: 99%

Charge-displacement analysis for excited states

Ronca

Pastore

Belpassi

et al. 2014

The Journal of Chemical Physics

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“…[13][14][15][16][17][18][19][20][21][22][23] Experimental data, on the other hand, has resisted to yield a conclusive picture. [5][6][7][8][9][10][11][12] From a different point of view, the possibility of aligning molecules in magnetic fields 24,25 and the question of the fundamental limits of the magnetic anisotropy energy that is responsible for a preferred axis of alignment of the magnetic moment naturally lead to diatomic molecules of 3d transition elements and their complexes.…”

mentioning

confidence: 99%

Electronic ground states of Fe2+ and Co2+ as determined by x-ray absorption and x-ray magnetic circular dichroism spectroscopy

Zamudio-Bayer

Hirsch

Langenberg

et al. 2015

The Journal of Chemical Physics

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“…Coupled-cluster [CCSD(T)] calculations [28] reported the nonet state to be lower in energy. The discrepancies have been discussed in detail by Angeli and Cimiraglia [27] who argued that the difficulty in uniquely determining the GS is related to a discontinuity in the total energy of the septet state as a function of bond length and could be resolved only by using a much larger active space, which is not possible at the moment. Quantum Monte Carlo calculations by Casula et al [29] also reported both spin states to be very close in energy and presented arguments in favor of a septet GS.…”

Section: Density-functional Theory Verses Quantum-chemical Methodsmentioning

confidence: 99%

Magnetic anisotropy of heteronuclear dimers in the gas phase and supported on graphene: relativistic density-functional calculations

Błoński¹,

Häfner²

2014

J. Phys.: Condens. Matter

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The structural and magnetic properties of mixed PtCo, PtFe, and IrCo dimers in the gas phase and supported on a free-standing graphene layer have been calculated using density-functional theory, both in the scalar-relativistic limit and self-consistently including spin-orbit coupling. The influence of the strong magnetic moments of the 3d atoms on the spin and orbital moments of the 5d atoms, and the influence of the strong spin-orbit coupling contributed by the 5d atom on the orbital moments of the 3d atoms have been studied in detail. The magnetic anisotropy energy is found to depend very sensitively on the nature of the eigenstates in the vicinity of the Fermi level, as determined by band filling, exchange splitting and spin-orbit coupling. The large magnetic anisotropy energy of free PtCo and IrCo dimers relative to the easy direction parallel to the dimer axis is coupled to a strong anisotropy of the orbital magnetic moments of the Co atom for both dimers, and also on the Ir atom in IrCo. In contrast the PtFe dimer shows a weak perpendicular anisotropy and only small spin and orbital anisotropies of opposite sign on the two atoms. For dimers supported on graphene, the strong binding within the dimer and the stronger interaction of the 3d atom with the substrate stabilizes an upright geometry. Spin and orbital moments on the 3d atom are strongly quenched, but due to the weaker binding within the dimer the properties of the 5d atom are more free-atom-like with increased spin and orbital moments. The changes in the magnetic moment are reflected in the structure of the electronic eigenstates near the Fermi level, for all three dimers the easy magnetic direction is now parallel to the dimer axis and perpendicular to the graphene layer. The already very large magnetic anisotropy energy (MAE) of IrCo is further enhanced by the interaction with the support, the MAE of PtFe changes sign, and that of the PtCo dimer is reduced. These changes are discussed in relation to the relativistic electronic structure of free and supported dimers and it is demonstrated that the existence of a partially occupied quasi-degenerate state at the Fermi level favors the formation of a large magnetic anisotropy.

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A multireference perturbation theory study on the Fe₂molecule: in quest of the ground state

Cited by 27 publications

References 40 publications

Charge-displacement analysis for excited states

Charge-displacement analysis for excited states

Electronic ground states of Fe2+ and Co2+ as determined by x-ray absorption and x-ray magnetic circular dichroism spectroscopy

Magnetic anisotropy of heteronuclear dimers in the gas phase and supported on graphene: relativistic density-functional calculations

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A multireference perturbation theory study on the Fe2molecule: in quest of the ground state

Cited by 27 publications

References 40 publications

Charge-displacement analysis for excited states

Charge-displacement analysis for excited states

Electronic ground states of Fe2+ and Co2+ as determined by x-ray absorption and x-ray magnetic circular dichroism spectroscopy

Magnetic anisotropy of heteronuclear dimers in the gas phase and supported on graphene: relativistic density-functional calculations

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A multireference perturbation theory study on the Fe₂molecule: in quest of the ground state