Clustering and ensembles inequivalence in the / and / mean-field Hamiltonian models
نویسندگان
چکیده
We investigate a model of globally coupled conservative oscillators. Two different algebraic potentials are considered that display in the canonical ensemble either a second (/) or both a second and a first-order phase transition separated by tricritical points (/). The stability of highly clustered states appearing in the low temperature/energy region is studied both analytically and numerically for the /-model. Moreover, long-lived out-of-equilibrium states appear close to the second-order phase transition when starting with ‘‘water-bag’’ initial conditions, in analogy with what has been found for the Hamiltonian mean-field model. The microcanonical simulations of the /-model show strong hysteretic effects and metastability near the first-order phase transition and a narrow region of negative specific heat. 2003 Elsevier B.V. All rights reserved. PACS: 05.20.–y; 05.45.–a
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