共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
V. I. Vovna V. V. Korochentsev A. A. Komissarov I. B. L’vov 《Russian Journal of Physical Chemistry B, Focus on Physics》2013,7(3):220-224
Density functional theory and photoelectron spectroscopy are used to study the electronic structure of nickel acetylacetonate Ni(acac)2. Based on the calculated energies and composition of the molecular orbitals and the pattern of localization of the electron density, the nature of the gas-phase photoelectron spectrum bands of Ni(acac)2 is examined, and a new interpretation of it is proposed. The energies of the Kohn-Sham orbitals are assigned to the experimental vertical ionization energies in the approximation of the extended Koopmans theorem, which enables, with consideration given to the dependence of the Koopmans defect on the nature of the electronic level, to obtain a good agreement between the calculated orbital energies and experimental data on ionization energies. 相似文献
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The valence band density of states for PbI2 is determined from X-ray and u.v. induced photoelectron spectra. It is shown that the band derived from Pb 6s states is at 8 eV binding energy and not at the top of the valence bands as suggested by band structure and charge density calculations. A rigid shift in the predominantly iodine 5p derived bands to lower binding energy brings the band structure calculations into essential agreement with experiment. Pb 5d core level binding energies determined here are used to derive core level exciton energies of 0.7 eV from published reflectivity spectra. 相似文献
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M. V. Ryzhkov V. A. Gubanov Yu. A. Teterin A. S. Baev 《Zeitschrift für Physik B Condensed Matter》1985,59(1):1-6
The electronic structure of the light RE oxides CeO2, Pr2O3 and Nd2O3 has been studied by the cluster discrete variational DV-X method and X-ray photoelectron spectroscopy. The interpretation of XPE spectra basing on the MO model is given. The various electronic states contributions to the chemical bonding in the oxides are investigated. 相似文献
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M. V. Ryzhkov V. A. Gubanov Yu. A. Teterin A. S. Baev 《Zeitschrift für Physik B Condensed Matter》1985,59(1):7-14
The electronic structure of the heavy RE sesquioxides from Sm2O3 to Lu2O3 has been studied by the cluster discrete variational X method and X-ray photoelectron spectroscopy. The interpretation of XPS spectra basing on the MO model is given. An analysis of the dependence of Ln 4f orbitals contribution to chemical bonding on the lanthanide atomic number and bond lengths is made. 相似文献
6.
The electronic structure for titanium and zirconium monocarbides have been calculated with the SCF MS Xα-cluster method. The results are compared with the experimental X-ray photoelectron spectra and augmented plane wave (APW) calculations. 相似文献
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Marisa Scrocco 《Journal of Electron Spectroscopy and Related Phenomena》1992,60(4):363-373
Specific information on the energy level diagram and on the energy forbidden gap of tetraphenylporphyrin and its Ni derivative has been obtained by means of electron energy-loss spectroscopy (EELS) and X-ray photoelectron spectroscopy techniques. Comparison of the free ligand and its metal derivative emphasizes the importance of the metal 3d levels in the conduction processes. The interband and plasmon transition present in the EELS spectra of these species are compared with the theoretically calculated energy level diagram and experimental data. 相似文献
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采用基于密度泛函理论的赝势投影缀加波方法, 对六种典型的二元晶体结构Rocksalt (RS), Cesiun-chloride (CC), Zinc-blende (ZB), Wurtzite (WZ), Iron-silicide (IS) 和Nickel-Arsenide (NA)的MnTe进行了计算研究. 通过比较六种结构的结合能, 确定了MnTe的基态结构是反铁磁的NA结构. 研究了这六种结构MnTe的电子结构、磁性, 并用Birch-Murnaghan状态方程拟合求得了各相结构的体弹性模量和相变压. 电子态密度表明, RS, CC和IS结构的MnTe为反铁磁导体, ZB, WZ和NA结构的MnTe均为反铁磁半导体. 相似文献
11.
T. M. Ivanova A. V. Naumkin A. V. Shchukarev A. A. Sidorov M. A. Kiskin V. M. Novotortsev I. L. Eremenko 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(4):520-526
Iron trimethylacetate complexes with different ligands have been investigated by X-ray photoelectron spectroscopy (XPS). The Fe 2p, Fe 3p, C 1s, O 1s, and N 1s spectra obtained at successive replacement of the Fe-O coordination bonds with Fe-N bonds have been analyzed. A satellite component is found in the spectra of iron trimethylacetate complexes, which is indicative of the high-spin state of FeII and FeIII iron atoms. The XPS data made it possible to determine the degree of covalence of the metal-ligand bonding and reveal two nonequivalent states for iron atoms. 相似文献
12.
E. F. Sheka B. S. Razbirin A. N. Starukhin D. K. Nel’son 《Optics and Spectroscopy》2007,102(3):432-441
A quantum-chemical analysis of the donor-acceptor properties of a C60 + dimethylenemethylamine binary system is performed. It is shown that the term of the intermolecular interaction is two-well, because of which the optimization of the system structure at the initial distances between the molecules of 0.21 nm or smaller leads to the formation of N-methylfullerenepyrrolidine C60. At initial distances exceeding 0.25 nm, a weakly bound charge transfer complex with almost complete retention of the properties of the individual molecules is formed. The low-temperature emission and absorption vibronic spectra of N-methylfullerenepyrrolidine C60 in the crystalline toluene matrix are studied experimentally. It is found that the absorption spectra of the fulleroid and pure fullerene in the region corresponding to the excitation of the lowest electronic states are generally similar. The difference observed between the low-frequency spectra agrees completely with the quantum-chemical analysis performed. 相似文献
13.
We report the electronic structure of monoclinic CuO as obtained from first principles calculations utilizing density functional theory plus effective Coulomb interaction (DFT + U) method. In contrast to standard DFT calculations taking into account electronic correlations in DFT + U gave antiferromagnetic insulator with energy gap and magnetic moment values in good agreement with experimental data. The electronic states around the Fermi level are formed by partially filled Cu 3d x²?y² orbitals with significant admixture of O 2p states. Theoretical spectra are calculated using DFT + U electronic structure method and their comparison with experimental photoemission and optical spectra show very good agreement. 相似文献
14.
Claudia Ambrosch-Draxl Robert Kouba Peter Knoll 《Zeitschrift für Physik B Condensed Matter》1997,104(4):687-691
We have performed first-principles band structure calculations in order to investigate vibronic and optical properties of YBa2Cu3O7. A formalism describing temperature dependent Raman spectra from such ab-initio results has been applied to the 500 cm?1 apex oxygen mode and its overtone in good agreement with experimental results. The dynamical matrix of the five A1g modes established by atomic-force calculations is studied in detail showing rather good agreement with experimental eigen-frequencies and normal coordinates. The effect of isotope substitutions on the phonon frequencies is investigated. We demonstrate that the calculated vibronic properties of high Tc materials are improved by applying a generalized gradient correction scheme for the treatment of exchange and correlation effects instead of the local-density approximation. 相似文献
15.
A. Yu. Kuznetsov A. V. Kruzhalov I. N. Ogorodnikov A. B. Sobolev L. I. Isaenko 《Physics of the Solid State》1999,41(1):48-50
The results of an investigation of the electronic structure of lithium tetraborate crystals using experimental (x-ray photoelectron
spectroscopy) and theoretical (quantum-chemical modeling) methods are reported. The experimental spectrum of the valence-band
states of the crystal lies 2–15 eV below the Fermi level and is due primarily to boron-oxygen groups (B4O9). The quantum-chemical calculations were performed self-consistently, using the standard variant of the scattered-wave method
in the model of a cluster embedded in a lattice of point charges. The data obtained on the partial contribution of the model
densities to the one-electron spectrum of the [B4O9]6 cluster make it possible to interpret the fine structure of the experimental spectrum of the valence-band states.
Fiz. Tverd. Tela (St. Petersburg) 41, 57–59 (January 1999) 相似文献
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The electroreflectance and thermoreflectance spectra of SnS single-crystals have been studied from 1.2 to 4.8 eV in polarized light for the E ? a and E ? b polarizations. The energy values of critical points have been determined from the experimental curves. 相似文献
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P. Oelhafen V.L. Moruzzi A.R. Williams D.S. Yee J.J. Cuomo U. Gubler G. Indlekofer H.-J. Gu¨ntherodt 《Solid State Communications》1982,44(12):1551-1555
The electronic structure of the amorphous alloys V36Zr64, Cr30Zr70 and Mn30Zr70 has been studied by photoelectron spectroscopy (UPS, XPS) and bandstructure calculations for the ordered analogs. The valence band photoelectron spectra and the calculated density of states reveal a large contribution to the state density at the Fermi level from the 3d metal. This behavior is characteristic of Zr based alloys with early 3d transition metals and differs from alloys with higher 3d electron numbers in which the 3d band is located at higher energies. The implications of the high density of states at EF of the amorphous Zr-(V, Cr, Mn) alloys for magnetism and the occurrence of superconductivity is discussed. 相似文献
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We report the first order Raman spectra of layer type semiconducting compounds SnS1.75Se0.25 and SnS1.75Se0.5. The two Raman active modes of each compound have been identified and on the basis of their observed symmetry assigned in accord with group theoretical predictions. The frequencies of the observed phonons show that the behaviour of these two solid solutions is of the two-mode type. 相似文献