Showing 31 - 40 of 232
We perform a linear dynamical stability analysis of a general hydrodynamic model of chemotactic aggregation [P.H. Chavanis, C. Sire, Physica A 384 (2007) 199]. Specifically, we study the stability of an infinite and homogeneous distribution of cells against “chemotactic collapse”. We discuss...
Persistent link: https://www.econbiz.de/10011060480
We compute numerically the distribution of energies Ω(E,N) for the XY-model with short- and long-range interactions. We find that in both cases the distribution can be fitted to the functional form: Ω(E,N)∼exp(Nφ(E,N)), with φ(E,N) an intensive function of the energy.
Persistent link: https://www.econbiz.de/10011060601
We discuss the non-Boltzmannian nature of quasi-stationary states in the Hamiltonian mean field (HMF) model, a paradigmatic model for long-range interacting classical many-body systems. We present a theorem excluding the Boltzmann–Gibbs exponential weight in Gibbs Γ-space of microscopic...
Persistent link: https://www.econbiz.de/10011060761
We numerically show that metastable states, similar to the quasi-stationary states found in the so-called Hamiltonian Mean Field Model, are also present in a generalized model in which N classical spins (rotators) interact through ferromagnetic couplings decaying as r−α, where r is their...
Persistent link: https://www.econbiz.de/10011061143
The thermodynamic properties of a classical d-dimensional spin-S Heisenberg ferromagnet, with long-range interactions decaying as r−p and in the presence of an external magnetic field, is investigated by means of the spectral density method in the framework of classical statistical mechanics....
Persistent link: https://www.econbiz.de/10011061256
We review simple aspects of the thermodynamic and dynamical properties of systems with long-range pairwise interactions (LRI), which decay as 1/rd+σ at large distances r in d dimensions. Two broad classes of such systems are discussed. (i) Systems with a slow decay of the interactions, termed...
Persistent link: https://www.econbiz.de/10011061430
We study, through molecular dynamics, a conservative two-dimensional Lennard-Jones-like gas (with attractive potential ∝r−α). We consider the effect of the range index α of interactions, number of particles, total energy and particle density. We detect negative specific heat when the...
Persistent link: https://www.econbiz.de/10011061534
The nonextensivity of a classical long-range Hamiltonian system is discussed. The system is the so-called α-XY model, a lattice of inertial rotators with an adjustable parameter α controlling the range of the interactions. This model has been explored in detail over the last years. For...
Persistent link: https://www.econbiz.de/10011061865
A stochastic one-dimensional cellular automaton with long range spatial interactions is introduced. In this model the state probability of a given site at time t depends on the state of all the other sites at time t−1 through a power law of the type 1/rα, r being the distance between sites....
Persistent link: https://www.econbiz.de/10011061908
One- and two-dimensional lattices of points are connected with long-range links, whose lengths are distributed according to P(r)∼r-μ. By changing the decay exponent μ one can go from d-dimensional short-range networks to ∞-dimensional networks topologically similar to random graphs. An...
Persistent link: https://www.econbiz.de/10011062380