1,322 research outputs found
A Mutual Attraction Model for Both Assortative and Disassortative Weighted Networks
In most networks, the connection between a pair of nodes is the result of
their mutual affinity and attachment. In this letter, we will propose a Mutual
Attraction Model to characterize weighted evolving networks. By introducing the
initial attractiveness and the general mechanism of mutual attraction
(controlled by parameter ), the model can naturally reproduce scale-free
distributions of degree, weight and strength, as found in many real systems.
Simulation results are in consistent with theoretical predictions.
Interestingly, we also obtain nontrivial clustering coefficient C and tunable
degree assortativity r, depending on and A. Our weighted model appears as
the first one that unifies the characterization of both assortative and
disassortative weighted networks.Comment: 4 pages, 3 figure
Shear viscosity of neutron-rich nucleonic matter near its liquid-gas phase transition
Within a relaxation time approach using free nucleon-nucleon cross sections
modified by the in-medium nucleon masses that are determined from an isospin-
and momentum-dependent effective nucleon-nucleon interaction, we investigate
the specific shear viscosity () of neutron-rich nucleonic matter near
its liquid-gas phase transition. It is found that as the nucleonic matter is
heated at fixed pressure or compressed at fixed temperature, its specific shear
viscosity shows a valley shape in the temperature or density dependence, with
the minimum located at the boundary of the phase transition. Moreover, the
value of drops suddenly at the first-order liquid-gas phase transition
temperature, reaching as low as times the KSS bound of .
However, it varies smoothly for the second-order liquid-gas phase transition.
Effects of the isospin degree of freedom and the nuclear symmetry energy on the
value of are also discussed.Comment: 6 pages, 5 figure
Spinon Fermi surface in a cluster Mott insulator model on a triangular lattice and possible application to 1T-TaS
1T-TaS is a cluster Mott insulator on the triangular lattice with 13 Ta
atoms forming a star of David cluster as the unit cell. We derive a two
dimensional XXZ spin-1/2 model with four-spin ring exchange term to describe
the effective low energy physics of a monolayer 1T-TaS, where the effective
spin-1/2 degrees of freedom arises from the Kramers degenerate spin-orbital
states on each star of David. A large scale density matrix renormalization
group simulation is further performed on this effective model and we find a
gapless spin liquid phase with spinon Fermi surface at moderate to large
strength region of four-spin ring exchange term. All peaks in the static spin
structure factor are found to be located on the "" surface of half-filled
spinon on the triangular lattice. Experiments to detect the spinon Fermi
surface phase in 1T-TaS are discussed.Comment: 5+11 pages, 4+13 figure
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