The canonical example of a quantum-mechanical two-level system is spin. The simplest
picture of spin is a magnetic moment pointing up or down. The full quantum properties of …

Equilibrium phase transitions may be defined as nonanalytic points of thermodynamic
functions, eg, of the canonical free energy. Given a certain physical system, it is of interest to …

Phase transitions are among the most impressive phenomena occurring in nature. They are
an example of emergent behavior, ie, of collective properties having no direct counterpart in …

A new basin-sampling scheme is introduced to obtain equilibrium thermodynamic properties
by combining results from global optimisation and parallel tempering calculations. Regular …

We compare phase transition (-like) phenomena in small model systems for both
microcanonical and canonical ensembles. The model systems correspond to a few classical …

The stationary points of the potential energy function of the φ 4 model on a two-dimensional
square lattice with nearest-neighbor interactions are studied by means of two numerical …

The investigation of the Hamiltonian dynamical counterpart of phase transitions, combined
with the Riemannian geometrization of Hamiltonian dynamics, has led to a preliminary …

The elsewhere surmized topological origin of phase transitions is given here important
evidence through the analytic study of an exactly solvable model for which both topology of …

We calculate exactly both the microcanonical and canonical thermodynamic functions
(TDFs) for a one-dimensional model system with piecewise constant Lennard-Jones type …

Exact solutions are obtained for the mean-field spherical model, with or without an external
magnetic field, for any finite or infinite number N of degrees of freedom, both in the …