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Y. F. Zhukovskii S. Bellucci S. Piskunov L. Trinkler B. Berzina 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(4):519-525
Defective single-walled BN nanotubes of armchair- and zigzag-type
chiralities with uniform diameter can be simulated using a total geometry
optimization for the 1D-periodic model. For calculations, we have applied
the formalism of localized Gaussian-type atomic functions using the
Hamiltonian containing hybrid (DFT+HF) non-local exchange-correlation
functional B3PW as implemented in CRYSTAL code. Single N vacancy as well as C and O
substitutes of N atom cause an appearance of the energy levels inside the BN
NT band gap accompanied by relaxation of the nearest atomic spheres closest
to the point defect and electronic charge redistribution around it. 相似文献
54.
S. Bellucci F. Carillo P. Onorato 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(4):509-515
We suggest a spin filter scheme using T-stub nanometric
crossjunctions patterned in two dimensional electron gases (2DEGs)
in the presence of spin orbit interaction (SOI).
We compare the effects of SOI arising from vertical confinement of charge carriers
in the well, Rashba or α-SOI, with SOI generated by lateral
confinement of the wire, β-SOI. We show that β coupling
can be more effective in generating a spin polarized current as
compared to α-SOI. We also compare the efficiency of the
T-stub filter with the one of the X shaped cross junction. 相似文献
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Francesco Bellucci Maio Valentino Tullio Monetta Luigi Nicodemo Jose Kenny Luigi Nicolais Jovan Mijovic 《Journal of Polymer Science.Polymer Physics》1995,33(3):433-443
Dielectric measurements were utilized to follow the advancement of cure in a bifunctional and a tetrafunctional epoxy/amine formulation. In deferance to earlier dielectric studies of cure, complex impedance was measured and used to calculate ionic resistivity. By using complex impedance we were able to separate, according to their frequency dependence, the contributions to overall polarization from electrode blocking layers, mobile charge carriers, and dipole relaxations. At any stage of cure, there is a unique frequency at which ionic resistivity can be singularly measured. Our approach does not involve trial-and-error frequency search, it measures dielectric response in real time, and is conducive to the development of phenomenological models based on equivalent circuits. Values of ionic resistivity measured at different cure time and temperature were used to quantify the progress of cure. Excellent agreement was reported between the calculated values of normalized degree of cure obtained by dielectric and calorimetric measurements. It was suggested that apart from the extrinsic conductivity by ionic impurities, an intrinsic mechanism which involves the reactive molecules contributes to the overall ionic conductivity. © 1995 John Wiley & Sons, Inc. 相似文献
57.
S. Bellucci 《Zeitschrift fur Physik C Particles and Fields》1992,54(4):565-572
We consider the discretization of aD=2 surface using polygons. We map the surface onto superspace and integrate over surfaces of arbitrary genus, obtaining a discretized version of the Green-Schwarz string inD=1. Taking an unusual critical limit of the supersymmetric matrix model involved, we construct exact solutions, to all perturbative orders, for the discretized superstring in one dimension, both when the target space is a real line and when the theory is represented in terms of matrix variables on a circle of finite radius. We comment on the behavior of the compactfied perturbative expansion under duality transformations.BITNET: BELLUCCI at IRMLNF 相似文献
58.
S. Bellucci 《Zeitschrift fur Physik C Particles and Fields》1989,41(4):631-636
We show that the identification of the conformal anomaly of the general bosonic two-dimensional non-linear σ-model as the generating functional for on-shell string scattering amplitudes is correct up toO(α′) terms. The absence, in the loop corrections to the spacetime effective action, of contributions from the explicit coupling to the dilaton field is suggested as a general feature for σ-models describing tree-level string physics. 相似文献
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Triethylamine and bromine in 1,2-dichloroethane give a non isolable 1:1 charge transfer complex with Kf>107 M?1, which undergoes a fast intramolecular oxidation to N,N-diethylethyldeneiminium bromide and hydrogen bromide. 相似文献