共查询到20条相似文献,搜索用时 10 毫秒
1.
N. Hiraoka H. Okamura H. Ishii I. Jarrige K. D. Tsuei Y. Q. Cai 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(2):157-162
Electronic excitations in transition-metal oxides MnO, FeO, CoO and NiO are investigated by inelastic X-ray scattering and
optical reflectivity measurements. The dielectric functions are derived from the experimental data as a function of the momentum
transfer, q. Based on the derived q-dependent dielectric functions, two types of the charge transfer excitations, i.e., dipolar
and non-dipolar charge transfer, are clearly identified. We show that the Mott gaps around 5 eV are defined by the former
whereas the latter occurs at higher energies of 8–12 eV. Based on a molecular orbital analysis, we associate the dipolar and
the non-dipolar excitations with non-local charge transfer and conventional charge transfer, respectively. These types of
excitations are shown to be common for the 3d metal monoxides. On the other hand, the dd excitations observed in NiO and CoO
at energy <4 eV do not appear in FeO and MnO. The reasons are addressed in this report. 相似文献
2.
N. Bouarissa 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(2):153-158
Dependencies of electronic structure and lattice properties of InN with zinc-blende structure on hydrostatic pressure are
presented based on band structures computed using the empirical pseudopotential method. The pressure behavior of the pseudopotential
form factors have been analyzed. The effect of pressure on the density of states has been examined. Trends in bonding and
ionicity under pressure are also discussed. Our results show as well that the absolute value of the Fourier transform of the
valence charge density might be useful in the prediction of the phase transition in zinc-blende materials.
Received 25 May 2001 and Received in final form 16 January 2002 相似文献
3.
M. Ilkhani M. R. Abolhassani M. Aslaninejad 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(1):21-28
The impacts of pressure on the structural and electronic properties of CeIn3 have been calculated. The calculations are performed in the presence and the absence of spin-orbit interaction as well as
GGA+U using density functional theory within the PBE-GGA approximation. It is shown that energy and density of states analyses
are considerably influenced by the spin-orbit interaction. The spin and orbital magnetic moments of Ce are calculated under
pressure up to 22 GPa. An almost linear relation is observed between the magnetic moment and the density of states of Ce-4f at Fermi level. At ambient pressure, a good agreement between the values of the electric field gradients, EFG, and bulk modulus
with experimental results is observed. The strongest anisotropy in charge distribution originates from In-5p orbital, which has the main contribution to EFG. 相似文献
4.
Summary This work reports the electronic structure of GaInAsSb quaternary alloy by recursion method. A five-orbital sp3s* per atom model was used in the tight-binding representation of the Hamiltonian. The local density of states (LDOS), integrated
density of states (IDOS) and structural energy (ST.E) were calculated for Ga, In, As and Sb sites in Ga0.5 In0.5 As0.5 Sb0.5 and GaInAsSb lattice matched to GaAs and the same alloy lattice matched to GaSb. There are 216 atoms in our cluster arranged
in a zincblend structure. The results are in good agreement with available information about the alloy. 相似文献
5.
A. Šimůnek J. Vackář K. Kunc J. Hutter 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(2):245-249
A soft, norm-conserving pseudopotential for carbon is presented and its performance tested by calculations on atomic states
and on diamond: electronic energy levels of different atomic configurations, equilibrium lattice constant, bulk modulus, and
the TA(X) frozen-phonon frequency are accurately reproduced. Convergence of the total energy of diamond with the size of the
plane-wave basis set is compared for several frequently used pseudopotentials, and it is shown that calculations with the
reported pseudopotential can be performed at considerably lower cost than with the other norm-conserving pseudopotentials,
without loosing the accuracy of the latter in predicting structural and dynamical properties. The rapid convergence of the
results with the plane-wave cutoff is comparable to the performance of the Vanderbilt's ultrasoft pseudopotentials. The transferability
of the pseudopotential to other electronic configurations is discussed.
Received 8 September 1999 相似文献
6.
B. Xu X. Li J. Sun L. Yi 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(4):483-487
Using first-principles calculations based on density-functional theory in
its local-density approximation, we investigated the Electronic structure,
ferroelectricity and optical properties of CaBi2Ta2O9 (CBT)
for the first time. It is found that CBT compound has an indirect band gap
of 3.114 eV and the O 2s and 2p states are strongly hybridized with the 6s
states of Bi which belong to the (Bi2O2)2+ planes. The quite
strong Ta–O and Bi–O hybridization is the primary source for
ferroelectricity. Our results imply that the interaction between Bi and O is
highly covalent. The anisotropy occurs mainly above 4 eV in the optical
properties. The different optical properties have been discussed. 相似文献
7.
G. Fischer E. Dormann 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(1):21-27
High-resolution 13C nuclear magnetic resonance with 1H cross polarization and 1H decoupling under magic angle spinning is measured for the quasi-one dimensional organic conductor diperylene hexafluorophosphate
(including tetrahydrofurane solvent molecules) at temperatures between 160 K and 270 K. Ab initio molecular orbital calculations are used for chemical shift analysis and for assignment of Knight shifted lines and individual
carbon positions. The coexistence of neutral perylene molecules and perylene radicals in the same radical cation salt is revealed.
From Knight and chemical shifts we were able to distinguish two inequivalent perylene radicals within the conducting stack.
The spin density distribution of the molecular electronic wave function is determined quantitatively for these radicals.
Received 29 June 1999 and Received in final form 4 November 1999 相似文献
8.
S. Massidda R. Monnier E. Stoll 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(4):645-649
The electronic structure and the Fermi surface BaB6 are studied as a function of doping in a conventional bandstructure approach based on the local density approximation to
density functional theory (LDA). In particular it is shown that magnetic breakthrough can occur between the two sheets of
the Fermi surface disconnected by electron-hole mixing and the spin-orbit interaction. It is further suggested that angle-resolved
photoemission will see a single ellipse in the (100) plane for certain doping values, due to the finite energy/momentum resolution
of the method. Transport properties, computed within Bloch-Boltzmann theory, are also presented. The bare plasma energy is
found to be 0.6 eV in the stoichiometric compound.
Received 23 May 2000 相似文献
9.
M. Manekar S. B. Roy 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(1):19-25
We investigate the electronic structure of
Sr2FeMoO6/SrTiO3 (SFMO/STO) multilayers using the
ab initio Full Potential Linearized Augmented Plane Wave
method in order to study their properties within the GGA and GGA+U methods. We examin more especially the role of the interface
on the magnetic and transport properties of these multilayers taking into account a possible Fe deficiency at the interface
and we show that bulk behaviour is rapidly recovered due to the strong localization of
the interfacial perturbation. For perfect interfaces, the whole structure is found half-metallic within the GGA+U method;
the situation
being ambiguous within the GGA method where SFMO is at the limit of being half-metallic depending on the structural deformation
induced by the STO layer. This leads us to the conclusion that such a system could be used as injection electrode and tunnel
barrier in magnetic tunnel junctions with a fully spin polarized injected current.
For Fe deficient interfaces, we show that the interfacial densities of states are nearly unpolarized showing that this kind
of
imperfection has potentially a strong impact on the properties
of the multilayers. 相似文献
10.
M. Taguchi F. Le Normand J. Hommet S. Rey G. Schmerber J.C. Parlebas 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(4):611-615
We study the change of the electronic structures of nickel silicides, Ni3Si and NiSi2, as well as nickel and silicon through the evolution of their valence band X-ray photoelectron spectra (v-XPS) both experimentally
and theoretically. The experimental spectra are compared to the total and partial densities of states using tight-binding
linear muffin-tin orbital method (TB-LMTO) in the atomic sphere approximation (ASA). Good agreement is found between theory
and experiment.
Received 10 July 2000 相似文献
11.
M. Said F. Ben Zid C.M. Bertoni Stefano Ossicini 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(2):191-199
The electronic properties of rare-earth arsenides have been calculated from first principles. In the calculations we have
treated the rare-earth f electrons both as core-like and as valence-like electrons. We consider the changes in the energy bands and in the density
of states near the Fermi level which are found to be relevant, except for the case of LuAs, and discuss this in relation with
the role played from the rare-earth 5d derived states. Moreover we show that the rare-earth 5d related bands are particularly sensitive to the variation of the lattice constant; change in the lattice constant of less
than 1% leads to a different behaviour with respect to the crossing of the rare-earth 5d derived bands and the As 4p derived bands along the Δ-direction. This point is discussed in connection with the possibility of having a semimetal-semiconductor
transition in the rare-earth arsenides.
Received 22 February 2001 相似文献
12.
S. Ramasubramanian M. Rajagoplan R. Thangavel J. Kumar 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(2):265-268
Elastic and Thermodynamical properties of Ti1-xZrxC have been investigated using LAPW + lo within the density-functional theory with the generalized gradient approximation.
We have studied the stability of the alloy Ti1-xZrxC as a function of Zr composition in rocksalt (B1) structure by calculating the elastic constants C11, C12 and C44 using the tetragonal and trigonal distortions. Mechanical properties such as Poisson ratio, bulk, shear and Young’s modulii
of Ti1-xZrxC are calculated. The Debye temperature and hardness are also computed for the first time to our knowledge for Ti1-xZrxC in various compositions. 相似文献
13.
Z. Q. Liu J. Ni 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):29-34
We have investigated the properties of SiCAlN quaternary
compounds composed of SiC and AlN polytypes by first-principle
calculations. We find that their band gaps have a large tunability
and are sensitive to the polytype structures. Their electronic
properties vary from wide-band-gap semiconducting to metallic due to
the complex charge transfer between the two constituents SiC and
AlN. The formation energies are also calculated. These results show
SiCAlN quaternary compounds have potential applications in the
electronic devices that can be tuned over a large wavelength range. 相似文献
14.
S. Ghosh B. Sanyal C.B. Chaudhuri A. Mookerjee 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(4):455-461
We study the electronic structure and magnetic properties of disordered bcc CoxFe1-x, CrxFe1-x and MnxFe1-x alloys in their ferromagnetic phases using the Augmented Space Recursion (ASR) technique coupled with the tight-binding linearized
muffin tin orbital (TB-LMTO) method. We calculate the density of states and magnetic moment of these alloys to show the variation
upon alloying Fe with the other neighbouring 3d transition metals using arguments based on charge transfer, exchange splitting and hybridization effects.
Received 10 April 2001 and Received in final form 15 August 2001 相似文献
15.
L. Theil Kuhn A.K. Geim J.G.S. Lok P. Hedegård K. Ylänen J.B. Jensen E. Johnson P.E. Lindelof 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(2):259-263
We present here the first magnetisation measurements on isolated single crystalline Fe-nanoparticles performed with a ballistic
Hall micro-magnetometer. The measurements have a sensitivity of and thus provide us the possibility to study the mechanisms of magnetisation reversal in a single nanoparticle. The magnetic
properties of the nanoparticles are influenced by their crystal structure and shape, and the presence of an oxide surface
layer. They exhibit curling of the magnetic moments, but also a novel hysteresis behaviour. The spin configurations found
for the system agree well with numerical calculations based on a Heisenberg Hamiltonian including the exchange and dipole
interaction and surface anisotropy.
Received: 1st September 1998 and Received in final form 21 June 1999 相似文献
16.
C. Acha M. Monteverde M. Núñez-Regueiro A. Kuhn M. A. Alario Franco 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(4):421-428
The electronic and positronic properties of the pentanary semiconductor alloys GaxIn1-xPySbzAs1-y-z lattice matched to GaSb have been studied. The electron wave function is calculated semiempirically using the pseudopotential
band model under the virtual crystal approximation. The positron wave function is evaluated under the point core approximation
for the ionic potential. Electronic and positronic quantities namely, electronic structure and band gaps, positron band structure,
effective mass and affinity, and electron-positron momentum densities have been predicted and their dependence on the phosphorus
composition has been discussed.
Received 30 August 2002 / Received in final form 12 February 2003 Published online 24 April 2003 相似文献
17.
Y. Duan M. Jungen 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(2):183-190
Density functional self-consistent spin-polarized calculations with the Discrete Variational Method were performed to obtain
the electronic structures of cadmium chalcogenide beryllosilicate sodalites Cd8[BeSiO4]6Z2 and their bulk materials CdZ (Z = S, Se, Te). Similar as their bulk materials, these sodalites are also semiconductors. From
their density of states and charge distributions, it was found that there is greater localization of the electron density
in the sodalites compared with that of the bulk. The band gaps in their bulk compounds are different from those in the sodalite
structures due to the electrons of Si, Be and O filled in. Different from their bulk materials, the d electrons of Cd play
an important role to form an unseparated valence band with all orbitals of other elements. The calculated magnetic moments
of these three materials are very small since all d atomic orbitals are fully occupied.
Received: 28 March 1997 / Revised: 18 July 1997 / Accepted: 9
September 1997 相似文献
18.
V.R. Galakhov M.A. Korotin N.A. Ovechkina E.Z. Kurmaev V.S. Gorshkov D.G. Kellerman S. Bartkowski M. Neumann 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(2):281-286
The electronic structure of LiMnO2 and Li2MnO3 was studied by means of X-ray photoelectron and soft X-ray emission spectroscopy. For LiMnO2, LSDA and LSDA+U calculations were carried out. The LSDA+U calculations are in rather good agreement with the measured valence-band structure as well as with the magnetic and electrical
properties of LiMnO2. It is shown that the band gap in LiMnO2 is determined by the charge-transfer effect.
Received 15 March 1999 and Received in final form 14 July 1999 相似文献
19.
The binding energy of excitonium negative ion for the ground1,3S-states in bulk semiconductors GaAs and ZnO in the hyperspherical coordinate method was found. Angular and radial correlations
between electrons in gerade and ungerade states were taken into account by channel functions, that are the eigenfunctions
of Hamiltonian on the surface of the sphere in the three-dimensional configuration space. Energy values were calculated using
the adiabatic and Born-Oppenheimer approximations. The obtained energy values are in agreement with those obtained using variational
method. 相似文献
20.
Summary Line profiles of Resonant Auger Electron Spectra produced by isolated resonances are analyzed by separating the contributions
due to the direct, resonant and interference terms and taking explicitly into account the effects due to the finite bandwidth
of the incident radiation. The mean kinetic energy of the emitted electron and the spectral width of the Auger lines are also
studied as functions of the parameters characteristic of the incident radiation. The general expressions derived by the theory
are applied to the analysis of the lineshapes produced by a specific electronic transition taken from the autoionization spectrum
of the CO molecule. 相似文献