18,666 research outputs found
Effect of external electric field on the charge density waves in one dimensional Hubbard superlattices
We have studied the ground state of the one dimensional Hubbard superlattice
structures with different unit cell sizes in the presence of electric field.
Self consistent Hartree-Fock approximation calculation is done in the weak to
intermediate interaction regime. Studying the charge gap at the Fermi level and
the charge density structure factor, we get an idea how the charge modulation
on the superlattice is governed by the competition between the electronic
correlation and the external electric field.Comment: 6 pages, 8 figures. accepted in Journal of Physics: Condensed Matte
Gap solitons with null-scattering
We study excitation of gap solitons under the conditions of coherent perfect
absorption (CPA). Our system consists of a symmetric periodic structure with
alternating Kerr nonlinear and linear layers, illuminated from both the ends.
We show near-total transfer of incident light energy into the gap solitons
resulting in null-scattering. We also report on the nonlinear super-scattering
(SS) states. Both the CPA and the SS states are shown to be characterized by
typical field distributions. Both the exact and the approximate results (based
on nonlinear characteristic matrix method) are presented, which show good
agreement
Resonance State Wave Functions of Be using Supersymmetric Quantum Mechanics
The theoretical procedure of supersymmetric quantum mechanics is adopted to
generate the resonance state wave functions of the unbound nucleus Be.
In this framework, we used a density dependent M3Y microscopic potential and
arrived at the energy and width of the 1.8 MeV (5/2) resonance state. We
did not find any other nearby resonances for Be. It becomes apparent
that the present framework is a powerful tool to theoretically complement the
increasingly important accelerator based experiments with unbound nuclei.Comment: 5 pages, 4 figures, Phys. Lett. B (2017
Cavity controlled spectral singularity
We study theoretically a PT-symmetric saturable balanced gain-loss system in
a ring cavity configuration. The saturable gain and loss are modeled by
two-level medium with or without population inversion. We show that the
specifics of the spectral singularity can be fully controlled by the cavity and
the atomic detuning parameters. The theory is based on the mean-field
approximation as in standard theory of optical bistability. Further, in the
linear regime we demonstrate the regularization of the singularity in detuned
systems, while larger input power levels are shown to be adequate to limit the
infinite growth in absence of detunin
Comparative study of the electron conduction in azulene and naphthalene
We have studied the feasibility of electron conduction in azulene molecule
and compared with that in its isomer naphthalene. We have used non-equilibrium
Green's function formalism to measure the current in our systems as a response
of the external electric field. Parallely we have performed the Gaussian
calculations with electric field in the same bias window to observe the impact
of external bias on the wave functions of the systems. We have found that, the
conduction of azulene is higher than that of naphthalene inspite of its
intrinsic donor-acceptor property, which leads a system to more insulating
state. Due to stabilization through charge transfer the azulene system can be
fabricated as a very effective molecular wire. Our calculations shows the
possibility of huge device application of azulene in nano-scale instruments.Comment: 6 pages, 8 figure
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