共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
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
3.
A. Ślebarski A. Jezierski M. Neumann S. Plogmann 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(4):519-523
The electronic structure of the Co2-xZrSn Heusler alloys has been studied by X-ray photoelectron spectroscopy (XPS). XPS valence band spectra can be compared with
ab initio electronic structure calculations using the linearized muffin-tin orbital (LMTO) method. The calculated magnetic moments
per Co atom agree well with the moments obtained from experiment. The LMTO calculations also show the energy shifts of the
Co, Zr and Sn valence electron states towards the Fermi level when the concentration of vacancies increases in these alloys.
Received 9 March 1999 and Received in final form 6 May 1999 相似文献
4.
H. Zheng Y. Wang G. Ma 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):61-69
The electronic structure of LaNi5 and its hydride LaNi5H7 are obtained using the self-consistent cluster-embedding calculation method. The Fermi level of LaNi5H7 is 5.172 eV higher than that of LaNi5. In both materials, the La 5d electrons locate nearby the Fermi levels, and make only a small contribution to the density of states (DOS) of the valence
bands. There is no significant charge transfer from La to Ni in LaNi5. But for LaNi5H7, there is a charge transfer of 1.16 electrons from La to H, and H atoms are combined mainly with Ni to form hybridized orbitals
in the energy regions far below the Fermi level. An explanation of hydrogenation of LaNi5 is proposed: It is easy for hydrogens to take off some localized La 5
d electrons near the Fermi level, and combine with Ni to form hybridized orbitals in lower energy regions. This process is
therefore in favor of energy, and forces a lattice expansion until the Fermi level rises to zero.
Received 13 July 2001 / Received in final form 10 December 2001 Published online 17 September 2002 相似文献
5.
S. Saib N. Bouarissa P. Rodríguez-Hernández A. Muñoz 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(4):435-438
We present a theoretical study of the structural properties, namely
lattice constant, bulk modulus and its pressure derivative of zinc-blende
GaxIn1-xN. The calculations are performed using first-principles
calculations in the framework of the density-functional-theory
within the local density approximation under the virtual
crystal approximation. The computed values are in good
agreement with the available experimental data. The composition dependence
of the studied quantities is examined. Besides, the deviation of the alloy
lattice constant from Vegard's law is evaluated. 相似文献
6.
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
7.
N. Bouarissa 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(2):139-143
Pseudopotential investigation of energy band gaps and charge distribution in quasi-binary (GaSb)1-x(InAs)x crystals has been reported. To the best of our knowledge, there had been no reported theoretical work on these materials.
In agreement with experiment, the quasi-binary crystals of interest showed a significant narrowing of the optical band gap
compared to the conventional GaxIn1-xAsySb1-y quaternary alloys (with x
= 1 -
y). Moreover, the absorption at the optical gaps indicated that (GaSb)1-x(InAs)x is a direct Γ to Γ band-gap semiconductor within a whole range of the x composition. The information derived from the present study predicts that the band gaps cross very important technological
spectral regions and could be useful for thermophotovoltaic applications.
Received 30 August 2002 Published online 1st April 2003
RID="a"
ID="a"Present address: Physics Department, University of M'sila, 28000 M'sila, Algeria e-mail: N_Bouarissa@yahoo.fr 相似文献
8.
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
9.
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
10.
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
11.
A.K. Ray J.C. Boettger 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):429-433
The linear combinations of Gaussian type orbitals fitting function (LCGTO-FF) method is used to study the electronic and geometrical
properties of plutonium monolayers with square and hexagonal symmetry. The effects of several common approximations are examined:
(1) scalar-relativity vs. full-relativity (i.e., with spin-orbit coupling included); (2) paramagnetic vs. spin-polarized; and (3) local-density approximation (LDA) vs. generalized- gradient approximation (GGA). The results indicate that spin-orbit coupling has a much stronger effect on the
monolayer properties compared to the effects of spin-polarization. In general, the GGA is found to predict a larger lattice
constant and a smaller cohesive energy compared to LDA predictions. We also find a significant compression of the monolayers
compared to the bulk, contradicting the only other published result on a Pu monolayer. The current result supports the existence
of a δ-like surface on α-Pu.
Received 17 October 2001 Published online 6 June 2002 相似文献
12.
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
13.
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
14.
Phase evolution of layered cobalt oxides versus varying corrugation of the cobalt-oxygen basal plane
A general spin-state model and a qualitative physical picture have been proposed for a class of lately synthesized layered
cobalt oxides (LCOs) by means of density functional calculations. As the plane corrugation of the cobalt-oxygen layer decreases,
the LCOs evolve from a high-spin (HS) superexchange-coupled antiferromagnetic (AFM) insulator to an almost-HS AFM/ferromagnetic
(FM) competing system where the FM coupling is mediated via the p-d exchange by an increasing amount of delocalized pdσ holes having mainly the planar O 2p character. It is tentatively suggested that the delocalized holes more than 0.3 per CoO2 basal square are likely necessary for the insulator-metal and/or AFM-FM transitions in the corrugation-weakened LCOs. A phase
control may be realized in LCOs by varying the plane corrugation (thus modifying the hole concentration) through an ionic-size
change of the neighboring layers on both sides of the cobalt-oxygen layer. In addition, a few experiments are suggested for
a check of the present model and picture.
Received 28 July 2002 / Received in final form 10 October 2002 Published online 31 December 2002 相似文献
15.
R. Capelli P. Monachesi R. Del Sole G.C. Gazzadi 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(1):117-123
The dielectric and the loss functions of Ni(111) are calculated by the Full Potential Linear Muffin Tin Orbitals (FPLMTO)
ab initio method whithin the three-layers model (vacuum/surface/bulk). Particular attention is devoted to determine surface and bulk
state contributions to the spectra. Good agreement is found with recent experimental EELS data on the Fe-covered Ni(111) surface.
Received 10 July 2002 Published online 19 November 2002 相似文献
16.
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
17.
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
18.
S. Haffner M. Dressel D. Groult C. Schlenker 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,24(2):167-175
The potassium doped monophosphate tungsten bronzes KxP4W8O32 are two-dimensional metals which show a metal-to-metal transition at a critical temperature which depends on the doping level.
The metal-to-metal transition is accompanied by the formation of a commensurate charge density wave with wave vector (π/b,0) which is independent of the doping level. Undoped P4W8O32, on the other hand, has two metal-to-metal transitions which are connected to the formation of incommensurate charge density
waves. We measured the infrared reflectivity of the series KxP4W8O32 (x
= 0 - 1.57) in the spectral range from 100 to 10 000 cm-1 for room temperature and well below the critical temperature. Polarization-dependent infrared spectra find a two-dimensional
behavior in the normal and the charge density wave state and show signatures of hybridization between one- and two-dimensional
conduction bands. In undoped P4W8O32 the essentials of the charge density wave state can be understood from the nesting vectors of the calculated Fermi surface
and two gaps are observed in the infrared spectra. The gap sizes are a factor of about 2.5 bigger than the predictions from
mean-field theory in the weak-coupling limit which suggests medium- or strong electron-phonon coupling. For potassium doped
KxP4W8O32 one gap is observed in the charge density wave state. The energetics of the charge density formation may be dominated by
the energy required for the lattice modulation.
Received 27 April 2001 and Received in final form 21 September 2001 相似文献
19.
C. Hébert M. Willinger D.S. Su P. Pongratz P. Schattschneider R. Schlögl 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(4):407-414
Band-structure (BS) calculations of the density of states (DOS) using the full potential augmented plane waves code WIEN97
were performed on the four single-valence vanadium oxides VO, V2O3, VO2 and V2O5. The DOS are discussed with respect to the distortions of the VO6 octahedra, the oxidation states of vanadium and the orbital hybridisations of oxygen atoms. The simulated oxygen K-edge fine
structures (ELNES) calculated with the TELNES program were compared with experimental results obtained by electron energy-loss
spectrometry (EELS), showing good agreement. We show that changes in the fine structures of the investigated vanadium oxides
mainly result from changes in the O-p DOS and not from the shift of the DOS according to a rigid band model.
Received 17 December 2001 / Received in final form 19 June 2002 Published online 13 August 2002 相似文献
20.
Yu.D. Glinka A.S. Zyubin A.M. Mebel S.H. Lin L.P. Hwang Y.T. Chen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):279-283
Photoluminescence (PL) from composites of 7- and 15-nm sized silica nanoparticles (SNs) and mesoporous silicas (MSs) induced
by 266- (4.66-) and 532-nm (2.33-eV) laser light has been studied at room temperature. The multiband PL from MSs in the range
of 1.0-2.1 eV is evidenced to originate from isolated bulk and surface non-bridging oxygens (NBOs) and from NBOs combined
with variously placed 1-nm sized pore wall oxygen vacancies (OVs). The nature and diversity of NBO light-emitters are confirmed
by ab initio calculations. The PL from SNs exhibits only a short wavelength part of the bands (1.5-2.1 eV) originated from isolated bulk
and surface NBOs. This fact indicates that the highly OV-bearing structures occur only in extremely thin (∼ 1 nm) silica layers.
The similarity of spectroscopic properties of silica-based nanoscale materials to those of surface-oxidized silicon nanocrystals
and porous silicon, containing silica-passivating layers of the same width, is discussed.
Received 20 November 2000 相似文献