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By introducing a hard aperture function into a finite sum of complex Gaussian functions, an approximate analytical expression for the two-dimensional off-axial Hermite-cosh-Gaussian beams passing through a rectangular apertured and misaligned paraxially ABCD optical system has been derived. The results provide more convenience for studying their propagation and transformation than the usual way by using diffraction integral directly. Some numerical simulations are also illustrated for the propagation characteristics of a two-dimensional off-axial Hermite-cosh-Gaussian beam through a rectangular apertured ABCD optical system. 相似文献
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M. Pletyukhov S. Konschuh 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(1):29-43
We analytically evaluate charge and spin density response functions of the
clean two-dimensional electron gas with Rashba spin-orbit coupling at finite
momenta and frequencies. On the basis of our exact expressions we discuss the
accuracy of the long-wavelength and the quasiclassical approximations. We also
derive the static limit of spin susceptibilities and demonstrate,
in particular, how the Kohn-like anomalies in their derivatives are related
to the spin-orbit modification of the Ruderman-Kittel-Kasuya-Yosida
interaction. Taking into account screening and exchange effects of the Coulomb
interaction, we describe the collective charge and spin density excitation
modes which appear to be coupled due to nonvanishing spin-charge response
function. 相似文献
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The ground- and first-excited states of magnetopolarons in two-dimensional quantum dots for all coupling strengths 总被引:2,自引:0,他引:2
B.S. Kandemir T. Altanhan 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(2):227-232
The ground- and first-excited state energies of a magnetopolaron in a two dimensional parabolic quantum dot are studied within
a variational calculation for all coupling strength. The Lee-Low-Pines-Huybrecht variational technique that is developed previously
for all coupling strength has been extented for polarons in a magnetic field. The dependence of the polaronic correction on
the magnetic field and the confinement length is investigated. The polarization potential and the renormalized cyclotron masses
as a function of electron-phonon coupling strength and the strength of both confinement potential and magnetic field are also
studied within the same approach.
Received 16 December 2002 / Received in final form 14 April 2003 Published online 4 June 2003
RID="a"
ID="a"e-mail: kandemir@science.ankara.edu.tr 相似文献
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The optical absorption spectra (d-d transition bands) and covalent effect of Ni2+ ions in octahedral sites of Ca3Sc2Ge3O12 crystal have been investigated by the full energy matrix based on the two spin–orbit coupling parameters model. The bond length of octahedral site is Ri?=?2.19 Å, which can be determined by the cubic crystal-field parameter and optical spectral data. The lattice distortion of the Ni2+ center in Ca3Sc2Ge3O12 crystal is also obtained from the calculations. In addition, the result has shown that the covalent effect of Ni2+ ion in the octahedral site of Ga3Sc2Ge3O12 is obvious and cannot be ignored. The calculated d-d transition bands agree well with that of the experimental findings, suggesting that the present methods can explain reasonably the optical spectral data and covalent effect of 3d8 ions in octahedral lattices. 相似文献
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In this work, the complete matrix of optical spectral levels in trigonal symmetry of 3d2 (3d8) ions are established on basis of strong field coupling mechanism by using two spin–orbit coupling parameters model. The contribution of the spin–orbit coupling of ligand to the optical spectra has been included in these formulas. As an application, the optical spectra of Cr4+ in Y2Ti2O7 and Y2Sn2O7 have been studied by the complete diagonalization (energy matrix) method. The covalent effect has been studied and the difficulty about Dq parameter in explanation of optical spectra of Cr-doped Y2Ti2O7 and Y2Sn2O7 is removed. The theoretical results are in good agreement with observed data. 相似文献