共查询到20条相似文献,搜索用时 15 毫秒
1.
D. V. Kolesnikov V. A. Osipov 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,49(4):465-470
The low-energy electronic structure of icosahedral
fullerenes is studied within the field-theory model. In the field
model, the pentagonal rings in the fullerene are simulated by two
kinds of gauge fields. The first one, non-abelian field, follows
from so-called K spin rotation invariance for the spinor field
while the second one describes the elastic flow due to pentagonal
apical disclinations. For fullerene molecule, these fluxes are
taken into account by introducing an effective field due to
magnetic monopole placed at the center of a sphere.
Additionally, the spherical geometry of the
fullerene is incorporated via the spin connection term. The exact
analytical solution of the problem (both for the eigenfunctions
and the energy spectrum) is found. 相似文献
2.
A. Srinivasan M. N. Huda A. K. Ray 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(2):227-236
Fullerene-like silicon nanostructures with twenty and twenty-four carbon
atoms on the surface of the Si60 cage by substitution, as well as
inside the cage at various orientations have been studied within the
generalized gradient approximation to density functional theory. Full
geometry optimizations have been performed without any symmetry constraints
using the Gaussian 03 suite of programs and the LANL2DZ basis set. Thus, for the
silicon atom, the Hay-Wadt pseudopotential with the associated basis set is
used for the core electrons and the valence electrons, respectively. For the
carbon atom, the Dunning/Huzinaga double zeta basis set is employed.
Electronic and geometric properties of these nanostructures are presented
and discussed in detail. Optimized silicon-carbon fullerene like
nanostructures are found to have increased stability compared to the bare
Si60 cage and the stability depends on the number and the orientation
of carbon atoms, as well as on the nature of silicon-carbon and
carbon-carbon bonding. 相似文献
3.
M. Yamada H. Nishihara 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):257-260
Biferrocene-modified gold nanoparticles
(Aun-BFc) comprising 1.7, 2.2 and 2.9 nm
in average core diameter, d,
were synthesized by a substitution reaction of octyl
thiolate-covered nanoparticles with biferrocene-terminated
alkanethiol, 1-(9-thiononyl-1-one)-1, 1-biferrocene (BFcS).
All sizes of Aun-BFc undergo two-step
oxidation reactions in 0.1 mol dm-3
Bu4NClO4-CH2Cl2
and consecutive potential scans including the second oxidation
process lead to the formation of an adhesive redox-active gold
nanoparticle film on an electrode. The thickness of the
Aun-BFc film is controllable by the
number of potential scans. The scanning tunneling microscope
images reveal that the Aun-BFc (d = 2.9 nm) film forms many domains of
the assembled Aun-BFcs, especially the
particles are isotropically assembled in line. 相似文献
4.
Y. P. Chen Y. E. Xie X. H. Yan 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,49(3):333-338
We have studied the transmission resonances for a confined array of
antidots, using the lattice Green's function method. Two kinds of resonant
peaks via quasibound states are found. One kind of resonant peak corresponds
to the split quasibound states. The split states originate from the
superposition of quasibound states respectively localized in different (T or
crossed) junctions, while the number of quasibound states in each junction
is associated with the arm-width of the junction. Electrons in these split
states are mainly localized in the junctions. The other kind of resonant
peaks correspond to the high quasibound states which exist in (transverse
and longitude) multi-period confined arrays of antidots. It is interesting
to note that electrons in some of the high quasibound states are mainly
localized in the intersection of the junctions rather than in the junctions
themselves. 相似文献
5.
C. McGinley S. Al Moussalami M. Riedler M. Pflughoefft H. Borchert M. Haase A.R.B. de Castro H. Weller T. Möller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):225-228
We describe photoemission results from pure and Sb-doped SnO2 nanoparticles deposited on gold substrates. Photoelectron spectra with synchrotron radiation were recorded for Sn 3d, Sb
3d and O 1s core levels and valence bands in the 500-1200 eV energy range. For pure SnO2 nanoparticles the surface is terminated by an oxygen rich layer with no obvious surface environment for Sn. When doped n-type
with 9.1% or 16.7% Sb, dopant atoms are concentrated near the surface of the nanoparticles. The valence state of the dopant
atoms is predominantly SbV. Plasmon satellite features are also observed in core level photoemission spectra and their intensity relative to the main
peak increases with increasing photon energy.
Received 30 November 2000 相似文献
6.
A. Tanaka R. Saito T. Kamikake M. Imamura H. Yasuda 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):229-232
We have performed the optical and photoelectron
spectroscopic studies of alkyl-passivated Si nanoparticles synthesized by a
solution route. The alkyl-passivated Si nanoparticle with mean diameter less
than about 2 nm exhibits a strong ultraviolet-blue photoluminescence.
Furthermore, we have directly investigated their electronic structures in
the vicinity of Fermi level by means of valence-band photoemission
measurements using synchrotron radiation. From these results, the detailed
optical properties and electronic structures of alkyl-passivated Si
nanoparticles are discussed. 相似文献
7.
A. Md. Asaduzzaman M. Springborg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):213-216
Using a parameterized density-functional tight-binding method we have calculated the electronic and structural properties
of Ge–Si nanoparticles. Starting with a spherical part of a zinc-blende/diamond crystal (with the center of the sphere at
the mid-point of a nearest-neighbour bond) we have constructed initial structures that subsequently were allowed to relax.
Structures consisting solely of Ge atoms or solely of Si atoms were studied, together with core-shell structures for which
one semiconductor forms a shell on the core of the other semiconductor. Moreover, homogeneous, ordered SiGe structures as
well as structures with a semisphere of one semiconductor and a semisphere of the other were also considered.
In analysing the results special emphasis is put on identifying particularly stable structures, on explaining the occurrence
of those, on the spatial distribution of the frontier orbitals, and on the variation of the total energy with structure and
composition. 相似文献
8.
E. S. Dy H. Kasai 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):241-245
We study the interaction between tin(II) porphyrin (SnPor) with platinum and
non-precious Group 8B metals (iron, cobalt and nickel) by density functional
theory and discuss the electronic properties of the resulting products. We
also model the interaction of the resulting compounds with water where
applicable. Our studies indicate that, SnPor-Ni possesses electronic
properties similar to SnPor-Pt, suggesting that it may possess similar
photocatalytic properties for reduction reactions, such as converting water
to hydrogen gas. 相似文献
9.
M. Imamura T. Miyashita A. Tanaka H. Yasuda Y. Negishi T. Tsukuda 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):233-236
We have carried out optical and X-ray photoemission
studies of the dendrimer-encapsulated Au nanoclusters. The
dendrimer-encapsulated Au nanoclusters are prepared by the chemical
reduction of Au ions loaded within the dendrimer templates.
Photoluminescence spectrum of the dendrimer-encapsulated Au nanoclusters with
diameter of about 1.0 nm shows the visible luminescence centered at about
2.8 eV. In addition, we have measured the nanocluster-size dependent
photoemission spectra in the valence-band region. From line shape analysis
of Au 4f X-ray photoemission spectra, Au 4f core-level spectra of
the dendrimer-encapsulated Au nanoclusters reflect the size dependent
chemical-states. From these results, we discuss electronic structures and
chemical states of the dendrimer-encapsulated Au nanoclusters. 相似文献
10.
L. Kipp 《Applied Physics A: Materials Science & Processing》2002,75(1):59-67
Photoelectron spectroscopy with synchrotron radiation employing high energy and angular resolutions is a very efficient tool
for experimental investigations of the electronic structure of solids and their surfaces. In addition to standard band-mapping
applications, photoemission intensity and line-shape analyses provide valuable information about wave functions, bonds and
interactions of a many-electron system. In this report we choose covalent semiconductor surfaces as well as metallic clean
and nanostructured surfaces of layered materials to serve as model systems for assessing the spatial origin of photoelectrons
and the three-dimensional shape of Fermi surfaces.
Received: 11 July 2001 / Accepted: 23 July 2001 / Published online: 3 April 2002 相似文献
11.
P. Scheier K. Sattler 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):347-349
Monolayer and bi-layer silicon nanoparticle (SiNP) films
with wide band gaps (up to 4 eV) have been produced in UHV with
narrow size distributions of particles with 2-4 nm diameters and
were studied using scanning tunneling microscopy (STM) and
spectroscopy (STS). The films then were manipulated by applying
different values for the tunneling resistance. Nanoparticle
fusion and fission processes allow to shape the particles in the
films in various ways and to write in white and black on the
film template. 相似文献
12.
L. Kronik R. Fromherz E. Ko G. Ganteför J. R. Chelikowsky 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):33-36
We compare experimentally measured and
ab initio computed
photoelectron spectra of negatively charged deuterated silicon
clusters (
, 4m10, 0n2) produced in a plasma environment.
Based on this comparison, we discuss the kinetics and
thermodynamics of the cluster formation and the effect of
deuterium on the geometrical and electronic structure of the
clusters. 相似文献
13.
M.P. Machado P. Piquini R. Mota 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):91-93
The geometric structures, energetics and electronic properties of the recently discovered BN nanocones are investigated using
first-principles calculations based on the density-functional theory. We have proposed one particular structure for BN nanocones
associated with the 240° disclination, derived by the extraction of four 60° segments, presenting as characteristic four pentagons at the apex and termination in two atoms. The cones are simulated by
three clusters containing 58 B plus N atoms and additional 12 H atoms to saturate the dangling bonds at the edge. The most
stable configuration is obtained when the two terminating atoms are one B and one N. For the cases where the two terminating
atoms are of the same kind, the tip with B atoms is determined to have lower binding energy than with N atoms. The local densities
of states of these BN nanocones are investigated and sharp states are found in the regions close (below and above) to the
Fermi energy.
Received 14 October 2002 / Received in final form 6 December 2002 Published online 11 February 2003
RID="a"
ID="a"e-mail: ppiquini@smail.ufsm.br 相似文献
14.
S. Bornemann J. Minár J. B. Staunton J. Honolka A. Enders K. Kern H. Ebert 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(3):529-534
We present results of magnetic torque calculations using the fully relativistic
spin-polarized Korringa-Kohn-Rostoker approach applied to small Co and Fe
clusters deposited on the Pt(111) surface. From the magnetic torque one can
derive amongst others the magnetic anisotropy energy (MAE). It was found that
this approach is numerically much more stable and also computationally less
demanding than using the magnetic force theorem that allows to calculate the
MAE directly. Although structural relaxation effects were not included our
results correspond reasonably well to recent experimental data. 相似文献
15.
B. Huber M. Moseler 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(3):485-489
We showed in a recent density functional study that small
palladium cluster on a MgO surface with F-centers can be oxidized
to epitaxial PdxOy nano-oxides below
room temperature [1].
Here, we employ density functional theory in order to explore
different methods for an experimental verification of the PdxOy
formation. The electronic density of states (DOS) of bare, O2-decorated and of oxidized palladium cluster was calculated.
For many cluster sizes a clear difference in the DOS could be observed allowing
for a detection of the oxidation with surface sensitive spectroscopic methods.
In addition, adsorption sites and stretch frequencies of a single CO molecule
on bare and oxidized Pd4 clusters were calculated.
While CO prefers hollow sites on Pd4, top
adsorption sites are found for Pd4O2. Markedly different CO stretch
frequencies indicate a possible discrimination of bare clusters and oxides
by Fourier transform infrared spectroscopy. 相似文献
16.
V. Kumar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):227-232
We report the recent findings of metal (M) encapsulated
clusters of silicon from computer experiments based on
ab initio total energy
calculations and a cage shrinkage and atom removal approach. Our
results show that using a guest atom, it is possible to wrap
silicon in fullerenelike (f)
structures, as sp2 bonding is not
favorable to produce empty cages unlike for carbon. Transition M
atoms have a strong bonding with the silicon cage that are
responsible for the compact structures. The size and structure
of the cage change from 14 to 20 Si atoms depending upon the
size and valence of the M atom. Fewer Si atoms lead to
relatively open structures. We find cubic,
f, Frank-Kasper (FK)
polyheral type, decahedral, icosahedral and hexagonal structures
for M@Sin with n = 12-16 and several different M
atoms. The magic behavior of 15 and 16 atom Si cages is in
agreement with experiments. The FK polyhedral cluster,
M@Si16 has an exceptionally large density
functional gap of about 2.35 eV calculated within the
generalized gradient approximation. It is likely to give rise to
visible luminescence in these clusters. The cluster-cluster
interaction is weak that makes such clusters attractive for
cluster assembled materials. Further studies to stabilize
Si20 cage with M = Zr, Ba, Sr, and Pb
show that in all cases there is a distortion of the
f cage. Similar studies on M
encapsulated germanium clusters show FK polyhedral and
decahedral isomers to be more favorable. Also perfect
icosahedral M@Ge12 and
M@Sn12 clusters have been obtained with
large gaps by doping with divalent M atoms. Recent results of
the H interaction with these clusters, hydrogenated silicon
fullerenes as well as assemblies of clusters such as nanowires
and nanotubes are briefly presented. 相似文献
17.
I. Vilfan 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(2):277-284
The properties of
nanowires were investigated with
ab initio calculations based on the density-functional theory.
The molecules build weakly coupled one-dimensional chains, like
and Mo6S9-xIx, and the crystals are
strongly uniaxial in their mechanical and electronic properties.
The calculated moduli of elasticity and resilience along the chain axis are
c11 = 320 GPa and ER = 0.53 GPa, respectively.
The electronic band structure and optical conductivity indicate
that the
crystals are good quasi-one-dimensional conductors.
The frequency-dependent complex dielectric tensor ε, calculated
in the random-phase approximation, shows a strong Drude peak in
ε∥, i.e., for the electric field polarised parallel to
the chain axis, and several peaks related to interband transitions.
The electron energy loss spectrum is weakly anisotropic and has a strong peak
at the plasma frequency ħωp ≈20 eV.
The stability analysis shows that
is metastable against the
formation of the layered
. 相似文献
18.
M.-H. Du L.-L. Wang A. Kolchin H.-P. Cheng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):323-326
The interaction of water with SiO
2 is an important problem in geophysics,
materials physics, and environmental science. In this paper, we
present recent results on studies of H
2
O-silica clusters from first-principles
Born-Oppenheimer molecular dynamics calculations. Bond strength
and chemical stability are investigated as a function of cluster
size and chemical composition. Both physisorption and
chemisorption of water molecules on the clusters are discussed
via analysis of energetics.
Calculations of clusters are compared with the results from
extended surfaces. The validity of clusters as models of
surfaces is discussed. 相似文献
19.
T. S. Li C. H. Lee M. F. Lin 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(1):45-50
The transport properties of finite length double-walled carbon nanotubes subject to the influences of
a transverse electric field and a magnetic field with varying polar angles
are investigated theoretically. The electrical conductance, thermal conductance and Peltier coefficient
dependences on the external fields and symmetric configuration are studied in linear response regime.
Prominent peak structures of the electrical conductance are predicted when varying the electric field strength.
The features of the
conductance peaks are found to be strongly dependent on the external fields and
the intertube interactions.
The heights of the electrical and thermal conductance peaks display the quantized behavior,
while those of the Peltier coefficient do not. The conductance peaks are found to be broadened
by the finite temperature. 相似文献
20.
S. Nonose S. Iwaoka H. Tanaka N. Okai T. Shibakusa K. Fuke 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):335-338
Photo-induced reaction of
[Fe(III)-protoporphyrin]+
(hemin+) ions solvated with
dimethylsulfoxide (DMSO) is investigated by using a tandem mass
spectrometer with electrospray ionization. We measure the
photodissociation yields of mass-selected
hemin+(DMSO)n
clusters for n = 0-3. The
mass spectra of the fragment ions show the -cleavage of
carboxymethyl groups in addition to the evaporation of solvent
molecules. Yield of the -cleavage reaction is found to depend
strongly on the excitation energy and the number of solvent
molecules. We also examine photo-induced reactions of
multiply-charged cytochrome c ions, (M + nH)n + (
n = 9-17). Photoionization is
found to be the dominant process for the lower charged states (
n = 9-12) and its yield
decreases rapidly with increasing the charge. The
photoionization is ascribed to the emission of electron by
multiphoton excitation of heme under the influence of Coulomb
attractive potential arising from the charges in the polypeptide
chain. Model calculations of the Coulomb potential suggest that
the structure of the polypeptide chain is completely elongated. 相似文献