102,535 research outputs found
Green's function method for single-particle resonant states in relativistic mean field theory
Relativistic mean field theory is formulated with the Green's function method
in coordinate space to investigate the single-particle bound states and
resonant states on the same footing. Taking the density of states for free
particle as a reference, the energies and widths of single-particle resonant
states are extracted from the density of states without any ambiguity. As an
example, the energies and widths for single-neutron resonant states in
Sn are compared with those obtained by the scattering phase-shift
method, the analytic continuation in the coupling constant approach, the real
stabilization method and the complex scaling method. Excellent agreements are
found for the energies and widths of single-neutron resonant states.Comment: 20 pages, 7 figure
Surface Impedance and Bulk Band Geometric Phases in One-Dimensional Systems
Surface impedance is an important concept in classical wave systems such as
photonic crystals (PCs). For example, the condition of an interface state
formation in the interfacial region of two different one-dimensional PCs is
simply Z_SL +Z_SR=0, where Z_SL (Z_SR)is the surface impedance of the
semi-infinite PC on the left- (right-) hand side of the interface. Here, we
also show a rigorous relation between the surface impedance of a
one-dimensional PC and its bulk properties through the geometrical (Zak) phases
of the bulk bands, which can be used to determine the existence or
non-existence of interface states at the interface of the two PCs in a
particular band gap. Our results hold for any PCs with inversion symmetry,
independent of the frequency of the gap and the symmetry point where the gap
lies in the Brillouin Zone. Our results provide new insights on the
relationship between surface scattering properties, the bulk band properties
and the formation of interface states, which in turn can enable the design of
systems with interface states in a rational manner
Research on 2×2 MIMO Channel with Truncated Laplacian Azimuth Power Spectrum
Multiple-input multiple-output (MIMO) Rayleigh fading channel with truncated Laplacian azimuth power spectrum (APS) is studied. By using the power correlation matrix of MIMO channel model and the modified Jakes simulator, into which with random phases are inserted, the effect of the azimuth spread (AS), angle of departure (AOD) and angle of arrival (AOA) on the spatial correlation coefficient and channel capacity are investigated. Numerical results show that larger AS generates smaller spatial correlation coefficient amplitude, while larger average AOD or AOA produces larger spatial correlation coefficient amplitude. The average capacity variation is comprehensively dominated by the average AOD, AOA and AS
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