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1.
B. A. Oli 《Il Nuovo Cimento D》1982,1(3):391-401
Summary A microscopic theory of the lattice dynamics of the transition metal niobium is developed to include local-field corrections
into the free-electron screening function. By a model potential transformation on the true Bloch wave functions, it was possible
to invert the dielectric matrix. In this way the lattice dynamics of niobium was computed to include effects arising from
the off-diagonal components of the matrix elements. The agreement between theory and experiment is good within the framework
of a microscopic theory.
Riassunto Si è sviluppata una teoria microscopica della dinamica reticolare del metallo di transizione niobio per includere correzioni di campo locale nella funzione di schermo per elettroni liberi. Mediante una trasformazione di potenziale modello delle vere funzioni d'onda di Bloch, è stato possibile invertire la matrice dielettrica. In questo modo è stata calcolata la dinamica reticolare del niobio per comprendere effetti derivati da componenti al di fuori della diagonale degli elementi di matrice. L'accordo tra teoria ed esperimenti è buono nell'ambito di una teoria microscopica.
Резюме Микроскопическая теория динамики решетки переходного металла, ниобия, обобщается, чтобы включить поправки локального поля в функцию экранирования свободными электронами. С помощью преобразования модельного потенциала по истинным блоховским волновым функциям оказывается возможным инвертировать диэлектрическую матрицу. В таком подходе при вычислении динамики решетки ниобия включаются эффекты, связанные с недиагональными компонентами матричных элементов. В рамках микроскопической теории получается хорошее согласие между теорией и экспериментом.相似文献
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W. Bardyszewski 《Journal of Physics and Chemistry of Solids》1983,44(8):813-817
The q and ω dependent dielectric function is examined in the random phase approximation for zinc-blende type, zero-gap semiconductors such as HgTe or HgSe. A detailed analysis of the properties of this function based on the analytical formulae obtained for the case of a highly degenerate free-electron gas is performed. In the limiting cases of the static and dynamic dielectric functions a comparison to previous theories is given. 相似文献
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《Chinese Journal of Physics (Taipei)》2018,56(5):2308-2316
Effects of electron-electron and electron-phonon optical interactions on the lattice dielectric function of the doped polar semiconductors are investigated. A new expression for the lattice contribution to the dielectric function is derived using the remarkable Zubarev double-time Green function. A numerical calculation for the case of GaN is done to highlight the accuracy of the model. The results obtained are in agreement with the available experimental data and reproduce the main features observed in Raman scattering spectra. 相似文献
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The effect of dynamical exchange interactions on the dielectric function of a two-dimensional electron gas is studied using a variational approach. Exchange effects are introduced via the local-field correction. The variationally obtained local-field factor is compared to the earlier perturbative result to first order in the electron-electron interaction. 相似文献
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The effect of dynamical exchange interactions on the dielectric function of a two-dimensional electron gas is studied using a variational approach. Exchange effects are introduced via the local-field correction. The variationally obtained local-field factor is compared to the earlier perturbative result to first order in the electron-electron interaction. 相似文献
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S. Schmitt-Rink D. B. Tran Thoai H. Haug 《Zeitschrift für Physik B Condensed Matter》1980,39(1):25-31
The optical dielectric function of an electron-hole plasma in highly excited polar semiconductors with a direct band gap is calculated by solving a Bethe-Salpeter equation for the polarization function. The screening of the Coulomb potential is treated in a damped phonon-plasmon-pole approximation. We include the complex dynamical self-energy corrections as well as electron-hole correlations.Project of the Sonderforschungsbereich Frankfurt/Darmstadt, financed by special funds of the Deutsche Forschungsgemeinschaft 相似文献
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J. Krupski 《Zeitschrift für Physik B Condensed Matter》1981,43(2):111-117
Using the random phase approximation and the Yafet wave functions the inter and intraband static dielectric functions of degenerate zero-gap semiconductors placed in a magnetic field are calculated in the long wavelength limit. It is shown that the values of the dielectric function for gapless semiconductors differ considerably from the result obtained previously for the one-band model with parabolic energy dispersion ands-type wave functions. Finally the dielectric function is used to find the static screening of a point impurity charge. 相似文献
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《Solid State Communications》1986,57(11):873-876
A closed analytic expression for the q and ω dependent dielectric function of the degenerate gas of holes in a zinc-blende or diamond structure semi-conductor is obtained in the random phase approximation (RPA). The limits of q → 0 and ω → 0 are examined and a comparison with previous developments is given. Significant deviations from the earlier results are found. 相似文献
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Bernreuther W Bonciani R Gehrmann T Heinesch R Leineweber T Mastrolia P Remiddi E 《Physical review letters》2005,95(26):261802
Interactions of heavy quarks, in particular, of top quarks, with electroweak gauge bosons are expected to be very sensitive to new physics effects related to electroweak symmetry breaking. These interactions are described by the so-called static form factors, which include anomalous magnetic moments and the effective weak charges. We compute the second-order QCD corrections to these static form factors, which turn out to be sizable and need to be taken into account in searches for new anomalous coupling effects. 相似文献
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Long-range Coloumb - and exchange interactions - leading to bound exciton states at the onset of the optical spectra of semiconductors and to Fano-type excitonic resonances in the continuum - and short-range Coulomb - and exchange interaction, that lead to a red shift in the low-energy part of the spectra as compared to one-particle calculations, are treated in a unified approach. Almost quantitative agreement between theoretical absorption spectra is obtained without any fitting parameter in the case of sc TlCl. 相似文献
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It is shown that a controlled concentration inhomogeneity causing a deviation of a laser beam incident on it can be produced
in some semiconductors. In indium antimonide, this effect appears in the case of temperature-electric instability in a magnetic
field. In a GaAs-GaP-based compound, this effect occurs due to the inbuilt gradient of static dielectric permittivity and
electron flow grouping. These effects make it possible to construct a deflector of infrared radiation. 相似文献
19.
Enhancement of the spontaneous decay rate due to local-field effects is estimated for a luminous dipole inside a small dielectric particle. To do this, we make use of an idea on multiplicativity of the local-field factor. Elongated particles are shown to be promising in respect of the local-field enhancement of the spontaneous emission. Computations are carried out within the framework of modern theory of the spontaneous decay of excited atoms in absorbing media for both the virtual-cavity and real-cavity models. Particular emphasis is placed on dielectric/semiconductor particles in the vicinity of the optical phonon frequencies. PACS 32.80.-t; 33.50.-j; 78.55.-m; 78.67.-nThis revised version was published in October 2004 with a new Figure 5. 相似文献
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《Solid State Communications》1986,59(7):485-490
A formalism is proposed that allows an efficient computation of the exchange-correlation functional including the nonlocal exchange and dynamical screening correctly. In combination with LDA band structures this functional leads to remarkably good results for semiconductors and even wide gap insulators. The model furthermore provides a qualitative understanding of electronic many-body effects. 相似文献