Structural,electronic, and magnetic properties of boron cluster anions doped with aluminum：BnAl-（2〈n〈9）

The geometrical structures, relative stabilities, electronic and magnetic properties of small BnAl-（2〈n〈9）clusters are systematicalyy investigated by using the first-principles density functional theory. The results show that the A1 atom prefers to reside either on the outer-side or above the surface, but not in the centre of the clusters in all of the most stable BnAl-（2〈n〈9） isomers and the one excess electron is strong enough to modify the geometries of some specific sizes of the neutral clusters. All the results of the analysis for the fragmentation energies, the second-order difference of energies, and the highest occupied-lowest unoccupied molecular orbital energy gaps show that B4A1- and B8A1- clusters each have a higher relative stability. Especially, the BsA1-cluster has the most enhanced chemical stability. Furthermore, both the local magnetic moments and the total magnetic moments display a pronounced oddeven oscillation with the number of boron atoms, and the magnetic effects arise mainly from the boron atoms except for the B7A1- and BgA1- clusters.     

Structural,electronic and magnetic properties of the Mn-Ni(110) c(2×2) surface alloy

<正>Using first-principles total energy method,we study the structural,the electronic and the magnetic properties of the MnNi(110) c(2×2) surface alloy.Paramagnetic,ferromagnetic,and antiferromagnetic surfaces in the top layer and the second layer are considered.It turns out that the substitutional alloy in the outermost layer with ferromagnetic surface is the most stable in all cases.The buckling of the Mn-Ni(110) c(2×2) surface alloy in the top layer is as large as 0.26 A(1 A=0.1 nm) and the weak rippling is 0.038 A in the third layer,in excellent agreement with experimental results.It is proved that the magnetism of Mn can stabilize this surface alloy.Electronic structures show a large magnetic splitting for the Mn atom,which is slightly higher than that of Mn-Ni(100) c(2×2) surface alloy(3.41 eV) due to the higher magnetic moment.A large magnetic moment for the Mn atom is predicted to be 3.81μB.We suggest the ferromagnetic order of the Mn moments and the ferromagnetic coupling to the Ni substrate,which confirms the experimental results.The magnetism of Mn is identified as the driving force of the large buckling and the work-function change.The comparison with the other magnetic surface alloys is also presented and some trends are predicted.     

The electronic and magnetic properties of （Mn,C）-codoped ZnO diluted magnetic semiconductor

The electronic and magnetic properties of (Mn,C)-codoped ZnO are studied in the Perdew-Burke-Ernzerhof form of generalized gradient approximation of the density functional theory. By investigating five geometrical configurations, we find that Mn doped ZnO exhibits anti-ferromagnetic or spin-glass behaviour, and there are no carriers to mediate the long range ferromagnetic (FM) interaction without acceptor co-doping. We observe that the FM interaction for (Mn,C)-codoped ZnO is due to the hybridization between C 2p and Mn 3d states, which is strong enough to lead to hole-mediated ferromagnetism at room temperature. Meanwhile, we demonstrate that ZnO co-doped with Mn and C has a stable FM ground state and show that the (Mn,C)-codoped ZnO is FM semiconductor with super-high Curie temperature (T C = 5475 K). These results are conducive to the design of dilute magnetic semiconductors with codopants for spintronics applications.     

The structural,electronic, and magnetic properties of SrFeOn（n=2 and 2.5）： a GGA＋U study

Using density-functional calculations within the generalized gradient approximation (GGA)+U framework,we investigate the structural,electronic,and magnetic properties of the ground states of SrFeOn (n = 2 and 2.5).The magnetism calculations show that the ground states of both SrFeO2 and SrFeO2.5 have G type antiferromagnetic ordering,with indirect band gaps of 0.89 and 0.79 eV,respectively.The electronic structure calculations demonstrate that Fe cations are in the high-spin state of (dz2 )2(dxz,dyz)2(dxy)1(dx2 y2 )1(S = 2),unlike the previous prediction of (dxz,dyz)3(dxy)1(dz2 )1(dx2 y2 )1(S = 2) for SrFeO2,and in the high-spin state of (dxy,dxz,dyz,dx2 y2 ,dz2 )5(S = 5/2) for SrFeO2.5.     

A density functional theory study on size-dependent structures,stabilities,and electronic properties of bimetallic M_nAg_m(M=Na,Li;n + m≤7) clusters

The equilibrium geometries,relative stabilities,and electronic properties of Mn Agm(M=Na,Li;n + m ≤ 7) as well as pure Ag n,Na n,Li n(n ≤ 7) clusters are systematically investigated by means of the density functional theory.The optimized geometries reveal that for 2 ≤ n ≤ 7,there are significant similarities in geometry among pure Ag n,Na n,and Li n clusters,and the transitions from planar to three-dimensional configurations occur at n = 7,7,and 6,respectively.In contrast,the first three-dimensional(3D) structures are observed at n + m = 5 for both Na n Ag m and Li n Ag m clusters.When n + m ≥ 5,a striking feature is that the trigonal bipyramid becomes the main subunit of Li n Ag m.Furthermore,dramatic odd-even alternative behaviours are obtained in the fragmentation energies,secondorder difference energies,highest occupied and lowest unoccupied molecular orbital energy gaps,and chemical hardness for both pure and doped clusters.The analytic results exhibit that clusters with an even electronic configuration(2,4,6) possess the weakest chemical reactivity and more enhanced stability.     

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.     

Probing structural and electronic properties of divalent metal Mgn+1 and SrMgn (n=2–12) clusters and their anions

Divalent metal clusters have received great attention due to the interesting size-induced nonmetal-to-metal transition and fascinating properties dependent on cluster size,shape,and doping.In this work,the combination of the CALYPSO code and density functional theory(DFT)optimization is employed to explore the structural properties of neutral and anionic Mg_n+1 and SrMgn(n=2-12)clusters.The results exhibit that as the atomic number of Mg increases,Sr atoms are more likely to replace Mg atoms located in the skeleton convex cap.By analyzing the binding energy,second-order energy difference and the charge transfer,it can be found the SrMg9 cluster with tower framework presents outstanding stability in a studied size range.Further,bonding characteristic analysis reveals that the stability of SrMg9 can be improved due to the strong s-p interaction among the atomic orbitals of Sr and Mg atoms.     

Structural,electronic and magnetic properties of gold cluster doped with calcium: Au n Ca (n = 1–8)

The geometrical structures, relative stabilities, electronic and magnetic properties of calcium-doped gold clusters Au _n Ca (n?=?1–8) have been systematically investigated by employing density functional method at the BP86 level. The optimised geometries show that the ground-state structures are planar structures for Au _n Ca (n?=?3–8) clusters. Ca-substituted Au _{n +1} clusters, as well as Au-capped Au _{n ?1}Ca clusters, are dominant growth patterns for the Au _n Ca clusters. The relative stabilities of Au _n Ca clusters for the ground-state structures are analysed based on the averaged binding energies, fragmentation energies and second-order difference of energies. The calculated results reveal that the Au₂Ca isomer is the most stable structure for small size Au _n Ca (n?=?1–8) clusters. The HOMO-LUMO energy gaps as a function of the cluster size exhibit a pronounced even–odd alternation phenomenon. Subsequently, charge transfers and magnetic moment of Au _n Ca (n?=?1–8) clusters have been analysed further.     

Density functional theory study of neutral AlS_n(n=2-9) clusters

This paper investigates the geometrical structures and relative stabilities of neutral AlS n(n = 2-9) using the density functional theory.Structural optimisation and frequency analysis are performed at the B3LYP/6-311G(d) level.The ground state structures of the AlS n show that the sulfur atoms prefer not only to evenly distribute on both sides of the aluminum atom but also to form stable structures in AlS n clusters.The structures of pure S n are fundamentally changed due to the doping of the Al atom.The fragmentation energies and the second-order energy differences are calculated and discussed.Among neutral AlS n(n = 2-9) clusters,AlS 4 and AlS 6 are the most stable.     

Density functional theory study of Mg_2Ni_n(n= 1–8) clusters

The density functional theory B3PW91 with LANL2DZ basis sets has been used to study the possible geometries of Mg2Nin(n = 1–8) clusters. For the lowest energy structures of the clusters, stabilities, electronic properties, and natural bond orbital(NBO) are calculated and discussed. The results show that the doped Mg atoms reduce the stabilities of pure Ni clusters. The Mg2Ni2, Mg2Ni4, and Mg2Ni6clusters are more stable than neighboring clusters. The system appears magic number characteristics. In addition, the hybridization phenomenon occurs, owing to the interaction of Mg and Ni. The result of charge transfer is that Ni atom is negative and the Mg atom is positive. We also conclude that the 3p and 4d orbitals of the Ni atom have an effect on the stabilities of the clusters.     

Geometric,stable and electronic properties of Aun-2Y2（n=3-8） clusters

Employing first-principles methods,based on the density function theory,and using the LANL2DZ basis sets,the ground-state geometric,the stable and the electronic properties of Aun-2Y2 clusters are investigated in this paper.Meanwhile,the differences in property among pure gold clusters,pure yttrium clusters,gold clusters doped with one yttrium atom,and gold clusters doped with two yttrium atoms are studied.We find that when gold clusters are doped by two yttrium atoms,the odd-even oscillatory behaviours of Aun-1Y and Aun disappear.The properties of Aun-2Y2 clusters are close to those of pure yttrium clusters.     

Structures and electronic properties of Mo2nNn（n=1-5）:a density functional study

The lowest-energy structures and the electronic properties of Mo2nNn(n=1-5) clusters have been studied by using the density functional theory(DFT) simulating package DMol 3 in the generalized gradient approximation(GGA).The resulting equilibrium geometries show that the lowest-energy structures are dominated by central cores which correspond to the ground states of Mo n(n = 2,4,6,8,10) clusters and nitrogen atoms which surround these cores.The average binding energy,the adiabatic electron affinity(AEA),the vertical electron affinity(VEA),the adiabatic ionization potential(AIP) and the vertical ionization potential(VIP) of Mo2nNn(n=1-5) clusters have been estimated.The HOMO-LUMO gaps reveal that the clusters have strong chemical activities.An analysis of Mulliken charge distribution shows that charge-transfer moves from Mo atoms to N atoms and increases with cluster size.     

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.     

First-principles calculations on the electronic and vibrational properties of β-V2O5

Using a first-principles approach based on density functional theory,this paper studies the electronic and dynamical properties of β-V2O5.A smaller band gap and much wider split-off bands have been observed in comparison with αV2O5.The Ramanand infrared-active modes at the Γ point of the Brillouin zone are evaluated with LO/TO splitting,where the symbol denotes the longitudinal and transverse optical model.The nonresonant Raman spectrum of a βV2O5 powder sample is also computed,providing benchmark theoretical results for the assignment of the experimental spectrum.The computed spectrum agrees with the available experimental data very well.This calculation helps to gain a better understanding of the transition from αto β-V2O5.     

Density functional study on chirospectra of hydrogen-bonded systems X-（H2O）3（X=F,Cl,Br,I）

This paper calculates the molecular structures,infrared,Raman,circular dichroism spectra and optical rotatory powers of some hydrogen-bonded supramolecular systems as a cyclic water trimer,(H2O)3 and its pyramidal halide complexes,X-(H2O)3(X = F,Cl,Br,I) with the gradient-corrected density functional theory method at the B3LYP/6-311++G(2d,2p) and B3LYP/Aug-cc-pVTZ levels.It finds that the complexation of halide anions with the water trimer can efficiently modulate the chirally optical behaviors.The calculated vibrational circular dichroism spectrum illuminates that the vibrational rotational strength of S(+)-(H2O)3 mostly originates from the O-H rocking modes,whereas chirality of S(-)-X-(H2O)3(X = F,Cl,Br,I) has its important origin in the O-H stretching modes.The calculated optical rotatory power demonstrates that S(+)-(H2O)3 and S(+)-F(H2O)3 are positively chiral,whereas S(-)-X-(H2O)3(X = Cl,Br,I) are negatively chiral.With the polarizable continuum model,calculated bulk solvent effect in the solvents water and carbontetrachloride and argon shows that the positive chirality of S(+)-(H2O)3 is enhanced and the negative chirality of S(-)-X-(H2O)3(X = Cl,Br,I) and the positive chirality of S(+)-F(H2O)3 are reduced with an augmentation of the solvent dielectric constant.     

Geometry and electronic properties of Cu2(n≤9)

The equilibrium geometries and the atomization energies of Cu_n(n≤9) clusters have been calculated using the B3LYP/LANL2DZ method. It is shown that the clusters do not copy the bulk structures and undergo significant geometrical changes with size and the atomization energy per atom increases monotonically with size. By analysing the energy level distribution, the Fermi level, HOMO－LUMO gaps, the electron affinities and the ionization potentials are calculated and the results are in reasonable agreement with experiment. These electronic properties are found to be strongly structure dependent, which can be used to determine which of the low-lying structures is observed experimentally.     

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...     

Structural, electronic and magnetic properties of the Mnben Ni(110) c(2×2) surface alloy

Using first-principles total energy method, we study the structural, the electronic and the magnetic properties of the MnNi(110) c(2×2) surface alloy. Paramagnetic, ferromagnetic, and antiferromagnetic surfaces in the top layer and the second layer are considered. It turns out that the substitutional alloy in the outermost layer with ferromagnetic surface is the most stable in all cases. The buckling of the Mn–Ni(110) c(2×2) surface alloy in the top layer is as large as 0.26á(1á=0.1 n13) and the weak rippling is 0.038 AA in the third layer, in excellent agreement with experimental results. It is proved that the magnetism of Mn can stabilize this surface alloy. Electronic structures show a large magnetic splitting for the Mn atom, which is slightly higher than that of Mn–Ni(100) c(2×2) surface alloy (3.41 eV) due to the higher magnetic moment. A large magnetic moment for the Mn atom is predicted to be 3.81 μ_B. We suggest the ferromagnetic order of the Mn moments and the ferromagnetic coupling to the Ni substrate, which confirms the experimental results. The magnetism of Mn is identified as the driving force of the large buckling and the work-function change. The comparison with the other magnetic surface alloys is also presented and some trends are predicted.     

Structural,electronic and magnetic properties of Fe(1−x)Cox alloy nanowires encapsulated inside (10,0) boron nitride nanotube

The structural, electronic and magnetic properties of Fe–Co alloy nanowires encapsulated inside zigzag (10,0) boron nitride nanotube (BNNT) are investigated by ab initio calculations. Similar to pristine nanotube, the opposite directional relaxations for the N atoms (move outwards) and B atoms (move inwards) from their initial positions are observed for outside BNNT although with the Fe–Co alloy nanowires inside, but the outward relaxations of the N atoms bonding to the Fe or Co atoms are smaller due to their attractions. The combining processes of Fe–Co/BNNT composites are endothermic when Co concentration x≤0.6 and exothermic x>0.6, and the most stable Fe–Co/BNNT composite is at Co concentration x=0.8. So the semiconducting (10,0) BNNT can be used to shield the Co-rich Fe–Co nanowires. The charges are transferred from Fe–Co nanowires to BNNT and the formed Co–N bonds have covalent bond as well as slight ionic bond characters. Although (10,0) BNNT is nonmagnetic and a decrease in the magnetic moment is found after Fe–Co nanowires are encapsulated inside (10,0) BNNT, the Fe–Co/BNNT composites still have large magnetic moment, reflecting they can be utilized in magnetic storage and ultra high-density magnetic recording devices.     

Structural stability and electronic properties of Au5Hn (n=1–10) clusters

A systematic study on the geometrical structures, electronic and magnetic properties of Au₅H _n (n=1–10) clusters has been performed by using the all-electron scalar relativistic density functional theory with generalized gradient approximation at the PW91 level. It is found that all Au₅H _n clusters prefer to keep the planar structures like pure Au₅ cluster, the Au₅ structures in Au₅H₄, Au₅H₅ and Au₅H₆ clusters are distorted obviously. The adsorption of a number of hydrogen atoms enhances the stability of Au₅ cluster and all Au₅H _n clusters are more stable than pure Au₅ cluster energetically. The odd-even alteration of magnetic moment is observed in Au₅H _n clusters and may be served as the material with tunable code capacity of “0” and “1” by adsorbing odd or even number of H atoms. It seems that the most favorable adsorption between Au₅ cluster and a number of hydrogen atoms takes place in the case that the odd number of hydrogen atoms is adsorbed onto Au₅ cluster and becomes Au₅H _n cluster with even number of valence electrons.