Structure and magnetic properties of FenGd clusters, n = 12 − 19 (original) (raw)
Related papers
Ab initio study of structural, electronic and magnetic properties of iron clusters Fen (n=2-13)
Revista Mexicana De Fisica, 2011
Structures, binding energies, and magnetic moments of Fen (n = 2–13) clusters have been obtained by pseudopotential density functional theory. A Troullier-Martin scheme was used to generate the iron’s pseudopotential and we have successfully reproduced results (lattice constant and magnetic moment) for the bulk BCC iron. The results indicate that the magnetic moment per atom varies slowly around a mean value 3.0 μB/atom. With increasing atom number the mean binding energy monotonically decreases.
Magnetic properties of small Pt-capped Fe, Co, and Ni clusters: A density functional theory study
Physical Review B, 2010
Theoretical studies on M 13 (M = Fe, Co, Ni) and M 13 Pt n (for n = 3, 4, 5, 20) clusters including the spin-orbit coupling are done using density functional theory. The magnetic anisotropy energy (MAE) along with the spin and orbital moments are calculated for M 13 icosahedral clusters. The angle-dependent energy differences are modelled using an extended classical Heisenberg model with local anisotropies. From our studies, the MAE for Jahn-Teller distorted Fe 13 , Mackay distorted Fe 13 and nearly undistorted Co 13 clusters are found to be 322, 60 and 5 µeV/atom, respectively, and are large relative to the corresponding bulk values, (which are 1.4 and 1.3 µeV/atom for bcc Fe and fcc Co, respectively.) However, for Ni 13 (which practically does not show relaxation tendencies), the calculated value of MAE is found to be 0.64 µeV/atom, which is approximately four times smaller compared to the bulk fcc Ni (2.7 µeV/atom). In addition, MAE of the capped cluster (Fe 13 Pt 4 ) is enhanced compared to the uncapped Jahn-Teller distorted Fe 13 cluster.
Journal of the American Chemical Society, 1995
Based on self-assembly of the dissymmetrical mononuclear entity CuL(CH 3 OH) [H 2 L = (E)-N 1-(2-((2-aminocyclohexydiimino)(phenyl)methyl)-4-chlorophenyl)-N 2-(2-benzyl-4-chlorophenyl)oxalamide] with Mn(II), two trinuclear complexes were prepared. They are of the formula [(LCuN 3) 2 Mn(CH 3 OH) 2 ] AE 2CH 3 OH AE 2H 2 O (1) and [(LCuSCN) 2 Mn(H 2 O) 2 ] AE 4CH 3 OH (2). Their magnetic properties were studied by susceptibility versus temperature measurement, the best fitting of the experimental data led to J = À14.40 cm À1 for 1 and J = À15.48 cm À1 for 2. Hydrogen bonds help complex 1 to produce a novel S type one-dimensional chain-like supramolecular structure. In complex 2, ClÁ Á ÁCl interaction also results in the formation of a one-dimensional structure.
BH-DFTB/DFT calculations for iron clusters
AIP Advances, 2016
A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements HWe present a study on the structural, electronic, and magnetic properties of Fe n (n = 2 − 20) clusters by performing density functional tight binding (DFTB) calculations within a basin hopping (BH) global optimization search followed by density functional theory (DFT) investigations. The structures, total energies and total spin magnetic moments are calculated and compared with previously reported theoretical and experimental results. Two basis sets SDD with ECP and 6-31G** are employed in the DFT calculations together with BLYP GGA exchange-correlation functional. The results indicate that the offered BH-DFTB/DFT strategy collects all the global minima of which different minima have been reported in the previous studies by different groups. Small Fe clusters have three kinds of packing; icosahedral (Fe 9−13 ), centered hexagonal antiprism (Fe 14−17
GGA/PBE study of the spin isomers of Fe34,40, Co23,34, and Co12Cu Clusters with Selected Geometries
Journal of the Mexican Chemical Society
In a recent beam deflecting experiment was found that high and low spin states of pure Fen and Con clusters with n ≤ 300 atoms coexist at cryogenic temperatures. In this work we have studied the high spin (HS) and low spin (LS) states of several structural isomers of Co23, Co34, Fe34, and Fe40 using the generalized gradient approximation (GGA) to density functional theory as implemented in the first-principles pseudo-potential code SIESTA. The calculated energy difference between these HS and LS isomers is not consistent with the observed coexistence, which can be due to an insufficient account of many body correlation effects in the GGA description, or to unknown isomer structures of these clusters. We have calculated within the same tools the magnetic isomers of Co12Cu cluster aimed to re-visit a former DFT prediction of an anti-ferromagnetic ground state. We find, however, a ferromagnetic ground state as expected on physical grounds. Our results exemplify the difficulties of the ...
The Electronic and Magnetic Properties of FCC Iron Clusters in FCC 4D Metals
Hyperfine Interactions, 2006
The electronic and magnetic structures of small FCC iron clusters in FCC Rh, Pd and Ag were calculated using the discrete variational method as a function of cluster size and lattice relaxation. It was found that unrelaxed iron clusters, remain ferromagnetic as the cluster sizes increase, while for relaxed clusters antiferromagnetism develops as the size increases depending on the host metal. For iron in Rh the magnetic structure changes from ferromagnetic to antiferromagnetic for clusters as small as 13 Fe atoms, whereas for Fe in Ag antiferromagnetism is exhibited for clusters of 24 Fe atoms. On the hand, for Fe in Pd the transition from ferromagnetism to antiferromagnetism occurs for clusters as large as 42 Fe atoms. The difference in the magnetic trends of these Fe clusters is related to the electronic properties of the underlying metallic matrix. The local d densities of states, the magnetic moments and hyperfine parameters are calculated in the ferromagnetic and the antiferromagnetic regions. In addition, the average local moment in iron-palladium alloys is calculated and compared to experimental results.
Structure, electronic and vibrational properties of Fe doped (M-X) clusters where M=Al, Ga & In and X-Sb are studied to investigate the changes in, when an electron is either added or removed from the corresponding neutral clusters by Density functional theory with the B3LYP exchange-correlation functional using DGDZVP as the basis set. Firstly geometrical optimizations of the nanoclusters have been done. Later on these optimized geometries are used to calculate the binding energy, HOMO-LUMO gap (band gap), electron affinity and ionization potential, chemical potential and chemical hardness of the clusters. The calculated results reveal that the any change in the configuration of clusters induces significant structural changes which might help in designing of new entities.
Magnetic properties of dodecanuclear mixed valence iron clusters
Inorganica Chimica Acta, 1996
Slow addition of dioxygen to a basic methanol solution of iron(II) chloride afforded the mixed valent polyiron oxo cluster [Fel2(O)2(O2CCH2CI)5.3CIo. 7 (CH30)Is(CH3OH)4] (1). The structure of 1 was determined in a single crystal X-ray diffraction study; crystallographic data at 202 K: space group Pi, a = 10.606(2)/~, b = 12.173(2) ]~, c = 13.199(1)/~, cr = 100.48(1) °, ff = 96.63(1) °, ? = 91.43(1) °, V= 1662.5(4)~3, Z= 1, Mr= 1907.3, Peale = 1.91 g cm -3. For 3499 unique observed reflections with F 2 > 3or(F2), R = 0.060, R w = 0.063. The core of the cluster contains a face-centered cubic array of oxygen atoms with eight iron(II) ions and four iron(Ill) ions occupying oetahedral sites. Two/~6-oxo ligands link 10 of the 12 iron atoms. The mixed valent nature of this air-sensitive compound was established by analyzing the Fe-O distances, by charge considerations, and by electronic and M6ssbauer spectroscopy. Three iron subsites are resolvable in the M6ssbauer spectrum, corresponding to localized Fe(III) and Fe(II) ions and consistent with the crystallographic data. The magnetic properties of 1 were satisfactorily reproduced by a simple model which assumes that exchange coupling interactions mediated by #2-methoxo ligands are responsible for the observed magnetic behavior in the temperature range 20-300 K, whereas at lower temperature the effects of the #3-methoxo,/~2-carboxylato and/~6-oxo ligands become more important. This behavior is reflected by the appearance of magnetic features in the M6ssbauer spectra with decreasing temperature. The magnetic properties of 1 may be understood as arising from two subclusters, a and b, for which the following two sets of parameters are proposed and discussed: (i) g(a)= 2.319(3), g(b)= 1.831(4), J= 15.9(1) cm -1 and (ii) g(a)= 2.23(3), g(b)= 2.1(1), J= 19(2) cm -1, where J is the exchange coupling constant through/~2-methoxo bridges within the a subcluster, and the spins of subeluster b remain largely uncoupled.
Magnetic structure of iron clusters and iron crystal surfaces
Surface Science, 2004
Electronic and magnetic properties of Fe atoms in a cluster of 89 atoms and at a (0 0 1) iron crystal surface are theoretically investigated within a fully-relativistic framework based on the local density approximation. The depthprofiles of the cluster and of the crystal surface exhibit different behaviour both as concerns the density of states and the spin and orbital magnetic moments. The convergence of local electronic and magnetic properties towards the bulk values is significantly faster for a planar surface than for a free cluster.