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1.
In the framework of the extended Hubbard model (copper-oxygen and oxygen-oxygen hopping) the energy and effective mass of a mobile hole is expressed in terms of hopping parameters and the correlators between spins of the background SnSn+1. Due to interaction of the mobile hole with localized holes, its effective mass increases about four times. 相似文献
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Correlated electron current and temperature dependence of the conductance of a quantum point contact
C. Sloggett A. I. Milstein O. P. Sushkov 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):427-432
We investigate finite temperature corrections to the Landauer formula
due to electron–electron interaction within the quantum point contact.
When the Fermi level is close to the barrier height, the conducting
wavefunctions become peaked on the barrier, enhancing the
electron–electron interaction. At the same time, away from the contact
the interaction is strongly suppressed by screening. To describe
electron transport we formulate and solve a kinetic equation for the
density matrix of electrons. The correction to the conductance G is
negative and strongly enhanced in the region 0.5 × 2e2/h ≤ G
≤ 1.0 × 2e2/h. Our results for conductance agree with the
so-called “0.7 structure” observed in experiments. 相似文献
4.
The electro-optical Kerr effect induced by a slowly varying electric field in liquid helium at temperatures below the lambda point is investigated. The Kerr constant of liquid helium is measured to be (1.43+/-0.02(stat)+/-0.04(sys)) x 10(-20) (cm/V)(2) at T=1.5 K. Within experimental uncertainty, the Kerr constant is independent of temperature in the range T=1.5 K to 2.17 K, which implies that the Kerr constant of the superfluid component of liquid helium is the same as that of normal liquid helium. Pair and higher correlations of He atoms in the liquid phase account for about 23% of the measured Kerr constant. Liquid nitrogen was used to test the experimental setup; the result for the liquid nitrogen Kerr constant is (4.38+/-0.15) x 10(-18) (cm/V)(2). Kerr effect can be used as a noncontact technique for measuring the magnitude and mapping out the distribution of electric fields inside these cryogenic insulants. 相似文献
5.
A method of calculating higher-order correlation corrections, using Green's functions and the Feynman diagrammatic technique, is developed. A basis of the single-electron orbitals is computed using the relativistic Hartree-Fock method. The interaction of an atom with an external field is computed by solving the time-dependent Hartree-Fock equations. In the methodology presented, we consider all the second-order correlation corrections and the dominating classes of higher order diagrams: the screening of the Coulomb interaction of electrons, particle-hole interaction and mass operator iterations. The calculation of the energy levels, the intervals of hyperfine structure and the amplitudes of the allowed EI-transitions in Cs shows that the method developed ensures precision at the 0.1–1% level. A calculation of the parity nonconservation of the El-amplitude of the transition 6s–7s in Cs is produced. The result <6s¦Dz¦7s> = –(0.91 ± 0.01)·10–11 i¦e¦aB (–QW/N) is obtained.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 108–119, August, 1990. 相似文献
6.
Three dominating subsequences of diagrams are summarized: (1) screening of the residual Coulomb interaction; (2) particle-hole interaction in the polarization operator; (3) chaining of the self-energy correction. An accuracy of 0.1% is obtained for the caesium energy levels. 相似文献
7.
V. G. Soloviev A. V. Sushkov N. Yu. Shirikova 《Zeitschrift für Physik A Hadrons and Nuclei》1997,358(3):287-296
M1 and E1 transition rates from the ground to excited states and between excited states in 238U are calculated within the quasiparticle-phonon nuclear model with the wave functions consisting of one- and two-phonon terms. We show that there are relatively large M1 transitions between 2+ states in the low-energy region. The fragmentation of the one-phonon states strongly affects M1 and E1 strength distributions. The correlation takes place between E1 and E3 transition strengths. We show that there are fast E1 and M1 transitions between large components of the wave functions differing by an octupole or quadrupole phonon. 相似文献
8.
We apply unrestricted Hartree-Fock to modelling two systems:
- (1)
- We calculate the spin structure and addition spectra of small symmetric quantum dots (often called 2D “artificial atoms”), improving the accuracy considerably by including, for the first time, second-order correlation corrections. We compare the results to experiment and to previous numerical works, and find that our spin structure in some cases disagrees with that calculated within mean-field theories, such as Hartree-Fock without correlation corrections, or density-functional theory [C. Sloggett, O.P. Sushkov, Phys. Rev. B 71 (2005) 235326].
- (2)
- We model the well-known 0.7 anomaly in the conductance of a quantum point contact. We calculate the conductance using direct calculation of scattering phases on a ring, within Hartree-Fock. We observe strong localisation of the Fermi electrons on the barrier, and suggest a mechanism for the observed temperature-dependent conductance anomaly.
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10.
S. I. Bastrukov A. Bonasera M. Di Toro A. V. Sushkov 《Zeitschrift für Physik A Hadrons and Nuclei》1991,338(4):455-456
It is shown that localization of the low-energy isoscalar 1? strength observed in a recent Groningen experiment may be caused by incompressible flow vibrations with considerable contribution of a solenoidal component. Calculations performed here without free parameters predict the energy of the isoscalar low-energy dipole resonance of the order of 40A ?1/3,Me V. This estimate agrees well with data obtained on 90Zrand 208Pb. 相似文献