Structure and magnetic properties of (Fe2O3)n clusters (n = 1–5)

Erlebach, Andreas; Hühn, Carolin; Jana, Rajkumar; Sierka, Marek

doi:10.1039/c4cp02099e

Cited by 39 publications

(41 citation statements)

References 77 publications

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“…This is another indication of how sensitive the interplay is between the chosen method and the spin configuration. For the larger molecules we note again good agreement in terms of bond lengths compared to the results of reference [32] as well as concerning the planarity of the obtained ground state structures up to Fe 3 O 4 [32,36,37].…”

Section: Structures and Energeticssupporting

confidence: 67%

“…Due to the unique properties of iron oxide nanoparticles and their applications [27][28][29][30], iron oxide clusters, as their building blocks, were subject to numerous theoretical studies focusing on energetic, geometrical and magnetic properties, see e.g. references [31][32][33][34][35][36][37]. While the structures reported by Jones et al [32] were used by us as input for structural optimisation (Sect.…”

Section: Introductionmentioning

confidence: 99%

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Electron impact ionisation cross sections of iron oxides

et al. 2017

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Abstract. We report electron impact ionisation cross sections (EICSs) of iron oxide molecules, FexOx and FexOx+1 with x = 1, 2, 3, from the ionisation threshold to 10 keV, obtained with the Deutsch-Märk (DM) and binary-encounter-Bethe (BEB) methods. The maxima of the EICSs range from 3.10 to 9.96 × 10 −16 cm 2 located at 59-72 eV and 5.06 to 14.32 × 10 −16 cm 2 located at 85-108 eV for the DM and BEB approaches, respectively. The orbital and kinetic energies required for the BEB method are obtained by employing effective core potentials for the inner core electrons in the quantum chemical calculations. The BEB cross sections are 1.4-1.7 times larger than the DM cross sections which can be related to the decreasing population of the Fe 4s orbitals upon addition of oxygen atoms, together with the different methodological foundations of the two methods. Both the DM and BEB cross sections can be fitted excellently to a simple analytical expression used in modelling and simulation codes employed in the framework of nuclear fusion research.

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Section: Structures and Energeticssupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Electron impact ionisation cross sections of iron oxides

et al. 2017

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“…4,6,9,10,[13][14][15][16][17][20][21][22][23][24]26 The number of works in which Fe m O n clusters were studied with methods beyond DFT is very limited and restricted to very small cluster sizes. For FeO + its reactivity towards H 2 was studied on a wave-function-based CASPT2D level.…”

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confidence: 99%

Geometric, electronic, and magnetic structure ofFexOy+clusters

Logemann¹,

Wijs²,

Katsnelson³

et al. 2015

Phys. Rev. B

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Correlation between geometry, electronic structure and magnetism of solids is both intriguing and elusive. This is particularly strongly manifested in small clusters, where a vast number of unusual structures appear. Here, we employ density functional theory in combination with a genetic search algorithm, GGA+U and a hybrid functional to determine the structure of gas phase Fe In nano technology there is an ever increasing demand for increasing the density of electronic and magnetic devices. This continuous downscaling trend drives the interest to electronic and magnetic structures at the atomic scale. In essence, two things are required: first, novel materials and building blocks with exotic physical properties. Second, a fundamental knowledge of the physical mechanism of magnetism at the sub-nanometer scale.Atomic clusters, having highly non-monotonous behavior as a function of size, are a promising model system to study the fundamentals of magnetism at the nanoscale and below. Such clusters consist of only tens of atoms. Quantum mechanics starts to play an essential role at this small scale, adding extra degrees of freedom. Since these clusters are studied in high vacuum, they are completely isolated from their environment.To use these clusters as a model system, as a starting point, a detailed understanding of the relation between their geometry and electronic structure is required.Even in the bulk, iron oxide has a wide variety of chemical compositions and phases with many interesting phenomena, such as the Verwey transition in magnetite. 1,2Experiments performed on small gas phase Fe x O y clusters beyond the two-atom case are scarce. The structure of one and two Fe atoms with oxygen has been studied in an argon matrix using infrared spectra.3,4 The corresponding vibration frequencies have been identified using density functional theory (DFT).Iron-oxide nanoparticles have been investigated for their potential use as catalyst in chemical reactions.5 Furthermore, since the iron-oxygen interaction has a fundamental role in many chemical and biological processes, there have been quite some studies, both experimental and theoretical, of the chemical properties of Fe x O y clusters. 6-12The possible coexistence of two structural isomers for stoichiometric iron-oxide clusters in the size range n ≥ 5 was experimentally measured using isomer separation by ion mobility mass spectroscopy for Fe n O n and Fe n O n+1 (n = 2-9).13 Furthermore, the formation of Fe x O y clusters has been studied in the size range (x = 1-52). 14The number of theoretical studies is, however, manifold. The magic cluster Fe 13 O 8 was extensively studied and identified as a cluster with C 1 but close to D 4h point group symmetry.15-19 However, also the geometry and electronic structure of other cluster sizes have been studied theoretically.15,20-25 The prediction of geometric structures requires a systematic search of the potential energy surface to find the global minimum.The majority of theoretical studies were performed using DFT. 4,6,9,1...

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“…We began our extensive search for the global minima on the potential energy surfaces with the geometrical structures generated for Ti 8 O 12 using the global search as well as the structures we previously generated for Fe 8 O 12 and the structures from other work When searching for the energetically preferred distributions of local spin magnetic moments in antiferromagnetic (AFM) singlet states of M 8 O 12 , we used the electronic density distributions obtained for the AFM states of other clusters as the guess. In addition, we also used the fragment method of the G09 program for generating various distributions of the total local spin magnetic moments.…”

Section: Details Of Computationsmentioning

confidence: 99%

“…Computations of the atomization energies of (MO 3 ) n (M Cr, Mo, W; n = 1-4), [37] as well as the energetic properties of groups 4 and 6 transition metal oxide nanoclusters, [38] and finally the binding energies using standard reference sets by a variety of different DFT and hybrid DFT methods have shown [39,40] the BPW91 accuracy to be comparable to that of more recently developed exchangecorrelation functionals. We began our extensive search for the global minima on the potential energy surfaces with the geometrical structures generated [15] for Ti 8 O 12 using the global search as well as the structures we previously generated [20] for Fe 8 O 12 and the structures from other work [17,18] When searching for the energetically preferred distributions of local spin magnetic moments in antiferromagnetic (AFM) singlet states of M 8 O 12 , we used the electronic density distributions obtained for the AFM states of other clusters as the guess. In addition, we also used the fragment method of the G09 program for generating various distributions of the total local spin magnetic moments.…”

Section: Details Of Computationsmentioning

confidence: 99%

Hydrogenation of 3d‐metal oxide clusters: Effects on the structure and magnetic properties

et al. 2018

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The geometrical structures and properties of the M8O12, M8O12H8, and M8O12H12 clusters are explored using density functional theory with the generalized gradient approximation for all 3d‐metals M from Sc to Zn. It is found that the geometries and total spin magnetic moments of the clusters depended strongly on the 3d‐atom type and the hydrogenation extent. More than the half of all of the 30 clusters had singlet lowest total energy states, which could be described as either nonmagnetic or antiferromagnetic. Hydrogenation increases the total spin magnetic moments of the M8O12H12 clusters when MMnNi, which become larger by four Bohr magneton than those of the corresponding unary clusters M8. Hydrogenation substantially affects such properties as polarizability, forbidden band gaps, and dipole moments. Collective superexchange where the local total spin magnetic moments of two atom squads are coupled antiparallel was observed in antiferromagnetic singlet states of Fe8O12H8 and Co8O12H8, whereas the lowest total energy states of their neighbors Mn8O12H8 and Ni8O12H8 are ferrimagnetic and ferromagnetic, respectively. Hydrogenation leads to a decrease in the average binding energy per atom when moving across the 3d‐metal atom series. © 2018 Wiley Periodicals, Inc.

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Structure and magnetic properties of (Fe₂O₃)_n clusters (n = 1–5)

Cited by 39 publications

References 77 publications

Electron impact ionisation cross sections of iron oxides

Electron impact ionisation cross sections of iron oxides

Geometric, electronic, and magnetic structure ofFexOy+clusters

Hydrogenation of 3d‐metal oxide clusters: Effects on the structure and magnetic properties

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