A Variational Approach to Monte Carlo Renormalization Group

by Roberto Car (Roberto Car, Princeton University, NJ 08544 USA and Department of Physics, Sapienza University of Rome, cattedra Enrico Fermi)

Monday 5 Jun 2017, 16:00 → 18:00 Europe/Rome

Aula Rasetti (Dipartimento di Fisica - Ed. G. Marconi)

Monte Carlo renormalization group (MCRG) calculations can be cast as a free energy sampling problem, using a variational principle recently formulated to enhance the sampling of the free energy in a space of coarse-grained collective variables. When applied to the coarse-grained variables in a renormalization group transformation the approach provides a direct way to compute the renormalized coupling constants and the critical exponents, generalizing the classical MCRG formalism introduced by Swendsen more than 30 years ago. In addition, the extra flexibility provided by the variational principle allows us to overcome the difficulties associated with critical slowing down. Calculations for the 2D Ising spin model will be used to illustrate the method.