Structural,electronic,and magnetic properties in FeAlAu_n(n=1–6)clusters:A first-principles study

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.     

Structural and electronic properties of small bimetallic Ag–Cu clusters

The structural and electronic properties of small gas-phase Ag_mCu_n clusters with m+n=2–5 atoms are investigated using spin-polarized density functional theory. The LANL2DZ effective core potential and the corresponding basis set are employed while the performance of several exchange-correlation functionals is assessed. For a given cluster size all possible compositions are subject to optimization using a variety of initial structures. The geometry, binding energy, relative stability, ionization potential, electron affinity and HOMO-LUMO gap are reported for the lowest energy structure of every cluster size and composition. The results show that planar structures are favored, triangular for trimers, rhombic for tetramers and trapezoidal for pentamers. Moreover, for tetramers and pentamers we found that silver atoms demonstrate a clear tendency to occupy edge positions. The calculation of electronic properties indicates that although all exchange-correlation functionals predict the same trends, the choice of method is crucial concerning the final quantitative results.     

Equilibrium geometries and electronic properties of BenLi （n=2-15） clusters from first principles

This paper studies the equilibrium geometries and electronic properties of Ben and BenLi clusters, up to n=15, by using density-functional theory（DFT） at B3LYP/6-31G（d） level. The lowest-energy structures of Ben and BenLi clusters were determined. The results indicate that a single lithium impurity enhances the stability and chemical reactivity of the beryllium clusters. It finds that the geometries of the host clusters change significantly after the addition of the lithium atom for n ≥8. The lithium impurity prefers to be on the periphery of beryllium clusters, and occupies vertex sites. Both Be4Li, Be9Li, and Be13Li were found to be particularly stable with higher average binding energy, local peaks of second-order energy difference and fragmentation energies. For all the BenLi clusters studied, we found charge transfers from the Li to Be site and co-existence of covalent and metallic bonding characteristics.     

First principles calculations of the structural and electronic properties of(CdSe)n clusters

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.     

Geometrical,electronic, and magnetic properties of CunFe (n=1–12) clusters: A density functional study

The geometrical, electronic, and magnetic properties of small Cu_nFe (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 Cu_nFe isomers tend to occupy the position with the maximum coordination number. The ground state Cu_nFe clusters possess planar structure for n=2–5 and three-dimensional (3D) structure for n=6–12. The electronic properties of Cu_nFe 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 Cu_nFe 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 Cu_nFe clusters show that Fe atom can enhance the magnetic moment of the host cluster and carries most of the total magnetic moment.     

Structural evolution and electronic properties of germanium-doped boron clusters and their anions: GeBn0/− (n = 6–20)

Journal of Nanoparticle Research - The creation of metal oxide aerogels is a demanded and developing area of science. Aerogel materials have a high specific surface area and can be used in a wide...     

A density functional theory study of small bimetallic PdnAl (n=1–8) clusters

The geometries, stabilities, and magnetic properties of Pd_nAl (n=1–8) neutral clusters are studied using density functional theory with generalized gradient approximation. The growth pattern for different sized Pd_nAl (n=1–8) clusters is Al-substituted Pd_n+1 clusters and it keeps the similar framework of the most stable Pd_n+1 clusters except n=6 and 8. Al atoms in the ground state Pd_nAl isomers tend to occupy the most highly coordinated position. The analysis of stabilities shows that doping an Al atom can enhance the stabilities of the host Pd clusters and the magic number characteristic of Pd₄ cluster cannot be changed, the Pd₃Al cluster has a higher stability. Charges are transferred from Al atom to Pd atoms in all Pd_nAl clusters, so the Al atom is the electron donor, and Pd atoms are the electron accepters. Doping an Al atom decreases the average atomic magnetic moments of the host Pd clusters.     

Geometrical,electronic, and magnetic properties of Au n V (n = 1–8) clusters: A density functional study

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.     

Geometries,stabilities, electronic and magnetic properties of small PdnIr (n = 1–8) clusters from first-principles calculations

The geometrical structures, relative stabilities, electronic and magnetic properties of small Pd_nIr (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 Pd_nIr 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 Pd_nIr clusters is mainly localised on the iridium atom for Pd_1–6Ir clusters. Meanwhile, the 5d orbital plays the key role in the magnetic moment of the iridium atom.     

Structure,stability and electronic properties of SrSi_n(n= 1–12) clusters::Density-functional theory investigation

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.     

Structural and bonding properties of ScSi_n~-(n=2～6) clusters:photoelectron spectroscopy and density functional calculations

Anion ion photoelectron spectroscopy and density functional theory (DFT) are used to investigate the electronic and structural properties of ScSi_n^- (n=2sim6) clusters and their neutrals. We find that the structures of ScSi_n^- are similar to those of Si_n+1^-. The most stable isomers of ScSi_n^- cluster anions and their neutrals are similar for n=2, 3 and 5 but different for n=4 and 6, indicating that the charge effect on geometry is size dependent for small scandium-silicon clusters. The low electron binding energy (EBE) tails observed in the spectra of ScSi_4,6^- can be explained by the existence of less stable isomers. A comparison between ScSi_n^- and VSi_n^- clusters shows the effects of metal size and electron configuration on cluster geometries.     

Structural,energetic and magnetic properties of small Ti<Subscript>n</Subscript> (n = 2–13) clusters: a density functional study

The structural, energetic, and magnetic properties of Ti _n clusters (n = 2 to 13 atoms) have been studied using Density Functional Theory (DFT), applying the pseudopotential LCAO method and the generalized gradient approximation for the exchange-correlation functional. The binding energy and the dissociation energy were calculated using the PBE and BLYP approximations for the exchange-correlation potential, in order to evaluate the performance of this functionals in predicting the energetic properties of small Ti clusters. The experimentally observed trend in the dissociation energy of Ti _n as a function of the cluster size is reproduced by both PBE and BLYP calculations. The effects of structural distortion on the magnetism of clusters were studied comparing the ground state structure against non-distorted clusters. It was found that the structural distortion has no effect on the total magnetic moment. For all studied clusters using the BLYP functional, with exception of Ti₆ and Ti₇, magnetism is predicted.     

Structural and electronic properties of SbnAl(0,±1) (n = 1–10) clusters using density-functional theory

We used the density functional theory (DFT) with the unrestricted B3LYP exchange-correlation potential and LanL2DZ basis sets to optimize the geometries of Sb_nAl and Sb_nAl^±1 (n = 1–10) clusters. We mainly utilized Gaussian 03 W software to calculate the data. In order to find the most stable structure of each isomer, we calculated the total energy, the spin multiplicity (S), point group symmetry (PG), the electronic state (State), and the average bond lengths of Sb-Al bond and Sb-Sb bond (R₁ and R₂). Through the calculations and analysis of these data, we found the ground state structure of each group isomer. By discussing the average binding energy (E_b), fragmentation energy (E_f), and the second-order energy difference (Δ₂E), the stabilities of the Sb_nAl ^(0,±1) clusters were studied. The results of the electron transfer show that the Sb₄Al and Sb₈Al clusters are different with the other neutral clusters. In order to study the electric properties of Sb_nAl ^(0,±1) clusters, the energy gap (E_g) between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), AEA, VDE, AIP, and VIP were calculated. Besides, the magnetic moment of the positive and negative clusters have the same effects when n = 2–9.     

Probing the structural and electronic properties of cationic rubidium–gold clusters: [AunRb]+ (n = 1–10)

Density functional theory has been applied to study the geometric structures, relative stabilities, and electronic properties of cationic [Au_nRb]⁺ and Au_{n + 1}⁺ (n = 1–10) clusters. For the lowest energy structures of [Au_nRb]⁺ clusters, the planar to three-dimensional transformation is found to occur at cluster size n = 4 and the Rb atoms prefer being located at the most highly coordinated position. The trends of the averaged atomic binding energies, fragmentation energies, second-order difference of energies, and energy gaps show pronounced even–odd alternations. It indicated that the clusters containing odd number of atoms maintain greater stability than the clusters in the vicinity. In particular, the [Au₆Rb]⁺ clusters are the most stable isomer for [Au_nRb]⁺ clusters in the region of n = 1–10. The charges in [Au_nRb]⁺ clusters transfer from the Rb atoms to Au_n host. Density of states revealed that the Au-5d, Au-5p, and Rb-4p orbitals hardly participated in bonding. In addition, it is found that the most favourable channel of the [Au_nRb]⁺ clusters is Rb⁺ cation ejection. The electronic localisation function (ELF) analysis of the [Au_nRb]⁺ clusters shown that strong interactions are not revealed in this study.     

First-principles calculations of the structural, electronic and magnetic properties of BnN20−n (n = 6−18) clusters

The structures of B _n N_20 ? 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 N_20?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.     

Geometries,stabilities and electronic properties of small-sized Pd2-doped Sin (n = 1–11) clusters

The geometries, growth patterns, relative stabilities and electronic properties of small-sized Pd₂Si_n and Si_n+2 (n = 1–11) clusters are systematically studied using the hybrid density functional theory method B3LYP. The optimised structures revealed that the lowest energy Pd₂Si_n clusters are not similar to those of pure Si_n clusters. When n = 9, one Pd atom in Pd₂Si₉ completely falls into the centre of the Si outer frame, forming metal-encapsulated Si cages. On the basis of the optimised structures, the averaged binding energy, fragmentation energy, second-order energy difference and highest occupied–lowest unoccupied molecular orbital energy gap are calculated. It is found that the Pd₂Si₅ and Pd₂Si₇ clusters have stronger relative stabilities among the Pd₂Si_n clusters. Additionally, the stabilities of Si_n+2 clusters have been reduced by the doping of Pd impurity. The natural population and natural electronic configuration analysis indicated that the Pd atoms possess negative charges for n = 1–11 and there exist the spd hybridisation in the Pd atom. Finally, the chemical hardness, chemical potential, electrostatic potential and polarisability are discussed.