Martín-Mayor, Víctor

Title: Monte Carlo simulations of (quasi) constrained ensembles
Author: Víctor Martín-Mayor
Affiliation: Universidad Complutense de Madrid, Spain
Abstract:
The standard Monte Carlo simulation of systems displaying metastability is very inefficient, (think of first-order phase transitions, spin glasses, structural glasses, lattice polymers, etc.). One may use constrained statistical ensembles in order to guide the simulation inside those rare but crucial regions where it does not want to get into. We combine a generalization of Lustig's microcanonical Monte Carlo with a fluctuation-dissipation formalism. Thermodynamic integration allows for an accurate reconstruction of the effective potential. Cluster algorithms can sometimes be made to work within this framework. In the context of the Statistical Mechanics of disordered systems, this approach amounts to a redefinition of the quenched average in terms of an effective potential, rather than Gibb's free energy. This choice automatically cures the rare-events syndrome that has hampered progress for quite a long time.