4,284 research outputs found
Two-orbital Systems with Crystal Field Splitting and Interorbital Hopping
The nondegenerate two-orbital Hubbard model is studied within the dynamic
mean-field theory to reveal the influence of two important factors, i.e.
crystal field splitting and interorbital hopping, on orbital selective Mott
transition (OSMT) and realistic compound CaSrRuO. A
distinctive feature of the optical conductivity of the two nondegenerate bands
is found in OSMT phase, where the metallic character of the wide band is
indicated by a nonzero Drude peak, while the insulating narrow band has its
Drude peak drop to zero in the mean time. We also find that the OSMT regime
expands profoundly with the increase of interorbital hopping integrals. On the
contrary, it is shown that large and negative level splitting of the two
orbitals diminishes the OSMT regime completely. Applying the present findings
to compound CaSrRuO, we demonstrate that in the doping
region from to 2.0, the negative level splitting is unfavorable to the
OSMT phase.Comment: 7 pages with 5 figure
Instability of small AdS black holes in sixth-order gravity
We investigate the stability analysis of AdS black holes in the higher
dimensional sixth-order gravity. This gravity is composed of Ricci cubic
gravity and Lee-Wick term. It indicates that the Ricci tensor perturbations
exhibit unstable modes for small AdS black holes in Ricci cubic gravity by
solving the Lichnerowicz-type linearized equation. We show that the correlated
stability conjecture holds for the AdS black hole by computing all
thermodynamic quantities in Ricci cubic gravity. Furthermore, we find a newly
non-AdS black hole in Ricci cubic gravity by making use of a static
eigenfunction of the Lichnerowicz operator.Comment: 27 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1801.0462
Instability of Reissner-Nordstr\"{o}m black hole in Einstein-Maxwell-scalar theory
The scalarization of Reissner-Nordstr\"{o}m black holes was recently proposed
in the Einstein-Maxwell-scalar theory. Here, we show that the appearance of the
scalarized Reissner-Nordstr\"{o}m black hole is closely related to the
Gregory-Laflamme instability of the Reissner-Nordstr\"{o}m black hole without
scalar hair.Comment: 22 pages, 10 figures, version to appear in EPJ
Stability of scalarized charged black holes in the Einstein-Maxwell-Scalar theory
We analyze the stability of scalarized charged black holes in the
Einstein-Maxwell-Scalar (EMS) theory with quadratic coupling. These black holes
are labelled by the number of , where is called the
fundamental black hole and denote the -excited black holes.
We show that the black hole is stable against full perturbations, whereas
the excited black holes are unstable against the -mode scalar
perturbation. This is consistent with the EMS theory with exponential coupling,
but it contrasts to the scalarized black hole in the
Einstein-Gauss-Bonnet-Scalar theory with quadratic coupling. This implies that
the endpoint of unstable Reissner-Nordstr\"{o}m black holes with
is the black hole with the same . Furthermore, we study the scalarized
charged black holes in the EMS theory with scalar mass .Comment: 23 pages, 11 figures. arXiv admin note: text overlap with
arXiv:1812.0360
Effects of interorbital hopping on orbital fluctuations and metal-insulator transitions: Extended linearized dynamical mean-field theory
We study the effects of interorbital hopping on orbital fluctuations and
Mott-Hubbard metal-insulator transition (MIT) in the two-orbital Hubbard model
within the extended linearized dynamical mean-field theory. By mapping the
model onto an effective model with different bandwidths through the canonical
transformation, we find that at half-filling, the increases of the interorbital
Coulomb interaction and the Hund's coupling drive the MIT, and
the critical for MIT increases with the lift of the inter-orbital
hopping integral . Meanwhile at quarter filling and in the strong
correlation regime, the system without exhibits MIT with the
decreasing of , and favors the orbital liquid ground state. However, the
system transits from metal to insulator with the increasing of t,
accompanied with the rising of the orbital order parameter. These results show
the important role of the interorbital hopping in the orbital fluctuation and
orbital ordering.Comment: 7 pages, 6 figure
On the impact of connected automated vehicles in freeway work zones: A cooperative cellular automata model based approach
PurposeFreeway work zones have been traffic bottlenecks that lead to a series of problems, including long travel time, high-speed variation, driver’s dissatisfaction and traffic congestion. This research aims to develop a collaborative component of connected and automated vehicles (CAVs) to alleviate negative effects caused by work zones. Design/methodology/approach\ua0The proposed cooperative component is incorporated in a cellular automata model to examine how and to what scale CAVs can help in improving traffic operations. Findings\ua0Simulation results show that, with the proposed component and penetration of CAVs, the average performances (travel time, safety and emission) can all be improved and the stochasticity of performances will be minimized too. Originality/valueTo the best of the authors’ knowledge, this is the first research that develops a cooperative mechanism of CAVs to improve work zone performance
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