title: Nonequilibrium phase transitions and violent relaxation in the Hamiltonian mean-field model.
abstract: We discuss the nature of nonequilibrium phase transitions in the Hamiltonian mean-field model using detailed numerical simulations of the Vlasov equation and molecular dynamics. Starting from fixed magnetization water bag initial distributions and varying the energy, the states obtained after a violent relaxation undergo a phase transition from magnetized to nonmagnetized states when going from lower to higher energies. The phase transitions are either first order or are composed of a cascade of phase reentrances. This result is at variance with most previous results in the literature mainly based on the Lynden-Bell theory of violent relaxation. The latter is a rough approximation and, consequently, is not suited for an accurate description of nonequilibrium phase transition in long-range interacting systems.
authors.affiliation: Instituto de Física and International Center for Condensed Matter Physics, Universidade de Brasília, Caixa Postal 04455, 70919-970 Brasília, Brazil.
authors.forename: T M
authors.initials: TM
authors.lastname: Rocha Filho
authors.forename: M A
authors.initials: MA
authors.lastname: Amato
authors.forename: A
authors.initials: A
authors.lastname: Figueiredo
mesh_terms: D003198:Computer Simulation; D056004:Molecular Dynamics Simulation; D044367:Phase Transition; D013816:Thermodynamics