Lattice animals with fugacities conjugate to the number of independent cycles, or to the number of nearest neighbour contacts, go through a collapse transition at a theta-point at a critical value of the fugacity. We examine the phase diagram of a model which includes both a cycle and a contact fugacity with Monte Carlo methods. Using an underlying cut-and-paste Metropolis algorithm for lattice animals, we implement in the first instance a multiple Markov chain simulation of collapsing animals to estimate the location of the collapse transitions and the values of the crossover exponents associated with these. Secondly, we use umbrella sampling to sample animals over a rectangle in the phase diagram to examine the structure of the phase diagram of these animals.
Collapsing animals
ORLANDINI, ENZO;
1999
Abstract
Lattice animals with fugacities conjugate to the number of independent cycles, or to the number of nearest neighbour contacts, go through a collapse transition at a theta-point at a critical value of the fugacity. We examine the phase diagram of a model which includes both a cycle and a contact fugacity with Monte Carlo methods. Using an underlying cut-and-paste Metropolis algorithm for lattice animals, we implement in the first instance a multiple Markov chain simulation of collapsing animals to estimate the location of the collapse transitions and the values of the crossover exponents associated with these. Secondly, we use umbrella sampling to sample animals over a rectangle in the phase diagram to examine the structure of the phase diagram of these animals.Pubblicazioni consigliate
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