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The structure and magnetic properties of Osn (n=11~22) clusters are systematically studied by using density functional theory (DFT). For each size, the average binding energy per atom, the second-order differences of total energies and the highest occupied molecular orbital (HOMO)–the lowest unoccupied molecular orbital (LUMO) gaps are calculated to analyze the stability of the cluster. The structures of Os14 and Os18 clusters are based on a close-packed hexagonal structure, and they have maximum stabilities, so n=14, 18 are the magic numbers. The 5d electrons play a dominant role in the chemical reaction of Osn clusters. The magnetic moments of Osn clusters are quenched around n=12, and when n=18~22 the value approximates to zero, due to the difference of electron transfer. 相似文献
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Structure,stability and electronic properties of SrSi_n(n= 1–12) clusters::Density-functional theory investigation
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Geometric structures, stabilities, and electronic properties of SrSin(n = 1–12) clusters have been investigated using the density-functional theory within the generalized gradient approximation. The optimized geometries indicate that one Si atom capped on SrSin 1structure and Sr atom capped Sinstructure for difference SrSinclusters in size are two dominant growth patterns. The calculated average binding energy, fragmentation energy, second-order energy difference, the highest occupied molecular orbital, and the lowest unoccupied molecular orbital(HOMO–LUMO) gaps show that the doping of Sr atom can enhance the chemical activity of the silicon framework. The relative stability of SrSi9is the strongest among the SrSinclusters. According to the mulliken population and natural population analysis, it is found that the charge in SrSin clusters transfer from Sr atom to the Sinhost. In addition, the vertical ionization potential, vertical electron affinity, and chemical hardness are also discussed and compared. 相似文献
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J. R. Li Y. W. Mu J. G. Wan F. Q. Song M. Han G. H. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(2):201-207
The structures of B n N20 ? n (n = 6?18), the clusters of boron nitride, are investigated by the density functional theory calculations. The structures of the obtained low-lying isomers can be described by the following six prototypes: single ring, double ring, three-ring, graphitic-like sheet, fullerene and others. B10N10 is demonstrated to be the most stable cluster against the nonstoichiometric ones. Nonzero magnetic moments, 1.999, 1.998, 2.000, 3.999 and 1.999μ B respectively, are found in five B n N20?n (n = 6, 7, 11, 12, 13) clusters. Further analysis indicates that the magnetic moment of the B6N14 cluster is mainly originated from the N atoms, while those of others are from the B atoms. The magnetic moment are finally attributed to the interesting issues of the 2p electrons due to the breaking of local symmetries, the change of coordination number, charge distribution and orbital hybridization. 相似文献
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In this paper various structural possibilities for AlnO neutral and cationic isomers were investigated by using the B3LYP/6-311G(3df) method. Calculations of this paper predicted the existence of a number of previously unknown isomers. The stabilities of the AlnO (n = 2 - 7) clusters with even n are greater than those with odd n, however the stabilities Of cationic ions have the opposite odd-even alternation. The mass spectra observations of Al17O^+ and Al19O^+ ions support our theoretical predictions on their stabilities. 相似文献
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Structure,stability and electronic properties of SrSin (n : 1-12) clusters: Density-functional theory investigationStructure,stability and electronic properties of SrSin (n : 1-12) clusters: Density-functional theory investigation
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Geometric structures, stabilities, and electronic properties of SrSin (n = 1-12) clusters have been investigated using the density-functional theory within the generalized gradient approximation. The optimized geometries indicate that one Si atom capped on SrSin_ 1 structure and Sr atom capped Sin structure for difference SrSin clusters in size are two dominant growth patterns. The calculated average binding energy, fragmentation energy, second-order energy difference, the highest occupied molecular orbital, and the lowest unoccupied molecular orbital (HOMO-LUMO) gaps show that the doping of Sr atom can enhance the chemical activity of the silicon framework. The relative stability of SrSi9 is the strongest among the SrSin clusters. According to the mulliken population and natural population analysis, it is found that the charge in SrSin clusters transfer from Sr atom to the Sin host. In addition, the vertical ionization potential, vertical electron affinity, and chemical hardness are also discussed and compared. 相似文献
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Structural,electronic,and magnetic properties in FeAlAu_n(n=1–6)clusters:A first-principles study
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《中国物理 B》2015,(6)
The geometries,electronic and magnetic properties of the trimetallic clusters Fe Al Aun(n = 1–6) are systematically investigated using density functional theory(DFT).A number of new isomers are obtained to probe the structural evolutions.All doped clusters show larger relative binding energies than pure Aun+2partners,indicating that doping with Fe and Al atoms can stabilize the Aun clusters.The highest occupied molecular orbital–lowest unoccupied molecular orbital(HOMO–LUMO) gaps,vertical ionization potentials and vertical electron affinities are also studied and compared with those of pure gold clusters.Magnetism calculations demonstrate that the magnetic moments of Fe Al Aun clusters each show a pronounced odd–even oscillation with the number of Au atoms. 相似文献
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M. X. Chen X. H. Yan S. Wei 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):513-517
Base on the density-functional theory, the structural and magnetic
properties of AunTi2
+ (
) clusters are investigated. The
two titanium atoms form a dimer in the gold clusters. The second-order
energy differences and HOMO-LUMO gap provide a clear explanation of the
abundance peaks and odd-even staggering observed recently in
photofragmentation experiments. The magnetism of AunTi2
+
cluster shows an odd-even effect when n increases from 1 to 4 and drops to
zero at n=5 and 7. The local magnetic moment and charge partition of Ti 4s,
3d orbitals are discussed. The peculiar magnetic properties are related to the
structures and the hybridization between the Au 5d, 6s states and Ti 3d, 4s
states. 相似文献
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The geometrical, electronic, and magnetic properties of small Au n V (n?=?1–8) clusters have been investigated using density functional theory at the PW91 level. An extensive structural search indicates that the V atom in low-energy Au n V isomers tends to occupy the most highly coordinated position and the ground-state configuration of Au n V clusters favors a planar structure. The substitution of a V atom for an Au atom in the Au n +1 cluster transforms the structure of the host cluster. Maximum peaks are observed for the ground-state Au n V clusters at n?=?2 and 4 for the size dependence of the second-order energy differences, implying that the Au2V and Au4V clusters possess relatively higher stability. The energy gap of the Au3V cluster is the largest of all the clusters. This may be ascribed to its highly symmetrical geometry and closed eight-electron shell. For ground-state clusters with the same spin multiplicity, as the clusters size increases, the vertical ionization potential decreases and the electron affinity increases. Magnetism calculations for the most stable Au n V clusters demonstrate that the V atom enhances the magnetic moment of the host clusters and carries most of the total magnetic moment. 相似文献
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Mao Ai-Jie Kuang Xiao-Yu Chen Gang Zhao Ya-Ru Li Yan-Fang Lu Peng 《Molecular physics》2013,111(11):1485-1494
The ab initio method based on density functional theory at the B3PW91 level has been applied to study the geometric, electronic, and magnetic properties of neutral and anionic Au n Pd (n?=?1–9) clusters. The results show that the most stable geometric structures adopt a three-dimensional structure for neutral Au7Pd and Au8Pd clusters, but for anionic clusters, no three-dimensional lowest-energy structures were obtained. The relative stabilities of neutral and anionic Au n Pd clusters were analysed by means of the dependent relationships between the binding energies per atom, the dissociation energies, the second-order difference of energies, the HOMO–LUMO energy gaps and the cluster size n, and a local odd–even alternation phenomenon was found. Natural population analysis indicates the sequential transfer from the Pd atom to the Au n frame in Au1,2,3,5Pd and Au2,3Pd? clusters, and from the Au n frame to the Pd atom in other clusters. Much to our surprise, irrespective of whether it is the total magnetic moment or the local magnetic moment, the magnetic moment presents an odd–even alternation phenomenon as a function of the cluster size n. The magnetic effects are mainly localized on the various atoms (Au or Pd) for different cluster size n. 相似文献
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The geometrical structures, relative stabilities, electronic and magnetic properties of small PdnIr (n = 1–8) clusters have been systematically investigated using density functional theory at the B3PW91 level. The optimised geometries show that the lowest-energy structures of PdnIr clusters prefer a three-dimensional configuration. The relative stability of these clusters was examined by analysis of the binding energies per atom, fragmentation energies, the second-order difference of energies and the HOMO–LUMO energy gaps as a function of cluster size. The obtained results exhibit that the Pd2Ir, Pd3Ir and Pd5Ir clusters are more stable than their neighbouring clusters. The energy gap of the Pd2Ir cluster is the largest of all the clusters (2.258 eV). In addition, the charge transfers, vertical ionisation potentials, vertical electron affinities and chemical hardness were calculated and discussed. The magnetism calculations indicate that the total magnetic moment of PdnIr clusters is mainly localised on the iridium atom for Pd1–6Ir clusters. Meanwhile, the 5d orbital plays the key role in the magnetic moment of the iridium atom. 相似文献
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The geometrical, electronic, and magnetic properties of small CunFe (n=1–12) clusters have been investigated by using density functional method B3LYP and LanL2DZ basis set. The structural search reveals that Fe atoms in low-energy CunFe isomers tend to occupy the position with the maximum coordination number. The ground state CunFe clusters possess planar structure for n=2–5 and three-dimensional (3D) structure for n=6–12. The electronic properties of CunFe clusters are analyzed through the averaged binding energy, the second-order energy difference and HOMO–LUMO energy gap. It is found that the magic numbers of stability are 1, 3, 7 and 9 for the ground state CunFe clusters. The energy gap of Fe-encapsulated cage clusters is smaller than that of other configurations. The Cu5Fe and Cu7Fe clusters have a very large energy gap (>2.4 eV). The vertical ionization potential (VIP), electron affinity (EA) and photoelectron spectra are also calculated and simulated theoretically for all the ground-state clusters. The magnetic moment analyses for the ground-state CunFe clusters show that Fe atom can enhance the magnetic moment of the host cluster and carries most of the total magnetic moment. 相似文献
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A systematic study on the structure and electronic properties of gold clusters doped each with one copper atom has been performed using the density functional theory. The average bond lengths in the Aun-1Cu (n ≤ 9) bimetallic clusters are shorter than those in the corresponding pure gold clusters. The ionization potentials of the bimetallic clusters Aun-1Cu (n 〈 9) are larger than those of the corresponding homoatomic gold clusters except for Aus. The energy gaps of the Au-Cu binary clusters are narrower than those of the Aun clusters except AuCu and Au3Cu. No obvious even-odd effect exists in the variations of the electron affinities and ionization potentials for the Aun-1Cu (n ≤ 9) clusters, which is in contrast to the case of gold clusters Aun. 相似文献
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WANG Xin-qiang CHEN Yong 《原子与分子物理学报》2004,21(Z1):211-212
The structural and electronic properties of (CdSe)n(1≤n≤5) clusters are calculated using density functional theory within the pseudopotential and generalized gradient approximations. The calculated binding energies and highest occupied molecular orbital lowest unoccupied molecular orbital gaps are compared with those obtained within local density approximation. 相似文献
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Chunjuan TangChunhe Zang Jianfeng SuDongmei Zhang Guanghai LiYongsheng Zhang Ke Yu 《Applied Surface Science》2011,257(8):3388-3391
In this paper we report the structure and magnetic properties of flower-like α-NiS nanostructure prepared by a facile one-step hydrothermal method. The flowers consist of polycrystalline nanoflakes, and the nanoflakes are composed of single crystalline nanocrystals with an average size of about 15 nm. The α-NiS flowers exhibit the transition from paramagnetism to ferromagnetism with the blocking temperature of about 12 K. The field dependences of the magnetization prove that these flowers demonstrate a coexistence of antiferromagnetism and ferromagnetism at 5 K, and exhibit a strong paramagnetic response at temperature higher than 100 K. 相似文献
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Kalavathy Santhi E. Thirumal S. N. Karthick Hee-Je Kim Marimuthu Nidhin V. Narayanan A. Stephen 《Journal of nanoparticle research》2012,14(5):868
Silver–nickel alloy nanoparticles with an average size of 30–40 nm were synthesized by chemically reducing the mixture of
silver and nickel salts using sodium borohydride. The structure and the magnetic properties of the alloy samples with different
compositions were investigated. The phase stability of the material was analysed after annealing the sample in vacuum at various
temperatures. The material exhibits single fcc phase which is stable up to 400 °C and Ni precipitation sets in when the sample
is annealed to 500 °C. The thermal analysis using DSC was carried out to confirm the same. The alloy compositions are found
to be in close correlation with the metal salt ratios in the precursors. The synthesized samples exhibit weak paramagnetic
to ferromagnetic behaviour. The magnetic measurements reveal that by adjusting the precursor ratio, the Ni content in the
material can be altered and hence its magnetic properties tailored to suit specific requirements. The formation of Ag–Ni alloy
is confirmed by the observed Curie temperature from the magneto thermogram. Annealing the sample helps to produce significant
enhancement in the magnetization of the material. 相似文献