RT Journal Article
T1 Ensemble equivalence in spin systems with short-range interactions
A1 Takahashi, Kazutaka
A1 Nishimori, Hidetoshi
A1 Martín Mayor, Víctor
AB We study the problem of ensemble equivalence in spin systems with short-range interactions under the existence of a first-order phase transition. The spherical model with nonlinear nearest-neighbour interactions is solved exactly both for canonical and microcanonical ensembles. The result reveals apparent ensemble inequivalence at the first-order transition point in the sense that the microcanonical entropy is non-concave as a function of the energy and consequently the specific heat is negative. In order to resolve the paradox, we show that an unconventional saddle point should be chosen in the microcanonical calculation that represents a phase separation. The XY model with non-linear interactions is also studied by microcanonical Monte Carlo simulations in two dimensions to see how this model behaves in comparison with the spherical model.
PB IOP Publishing
SN 1742-5468
YR 2011
FD 2011-08-30
LK https://hdl.handle.net/20.500.14352/42758
UL https://hdl.handle.net/20.500.14352/42758
LA eng
NO © 2011 IOP Publishing Ltd and SISSA.
DS Docta Complutense
RD 7 abr 2025