Metropolis Algorithm and integration volume

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SUMMARY

The Metropolis algorithm effectively evaluates canonical expectation value integrals by sampling from the Boltzmann density, despite common assumptions of infinite volume. In the canonical ensemble, the volume V is finite and constant, yet implementations often disregard this constraint, leading to correct results. The finite time of simulations limits the effective volume covered, which is normalized in the expectation value calculation. This understanding clarifies why accurate results can still be achieved without strict adherence to volume restrictions.

PREREQUISITES
  • Understanding of the Metropolis algorithm
  • Familiarity with canonical ensemble concepts
  • Knowledge of Boltzmann density and expectation values
  • Basic principles of Monte Carlo simulations
NEXT STEPS
  • Research the implementation details of the Metropolis algorithm in Monte Carlo simulations
  • Explore the implications of finite volume in statistical mechanics
  • Study normalization techniques for expectation values in simulations
  • Examine the referenced paper on Monte Carlo implementations for practical insights
USEFUL FOR

Researchers in statistical mechanics, physicists utilizing Monte Carlo methods, and anyone interested in the application of the Metropolis algorithm for evaluating integrals in finite systems.

Derivator
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Hello,

the Metropolis algorithm can be used to evaluate canonical expectation value integrals by sampling from the Boltzmann density. In the canonical ensemble, one has a finite and constant volume V, over which the configurational part of the expectation-value integral is integrated over.

However, in all descriptions and implementations of the Metropolis-Algorithm, I have never seen that such a volume restriction is obeyed. Everybody just seems to assume that the simulated particles can move freely in an infinite volume. Could someone explain, why one obtains correct results, despite not obeying finite volume constraints? Is this, because the simulation can (in practice) only be executed for a finite time, and hence it will only cover a finite (but large) volume (and this volume, because it is still finite, is canceled by the normalization of the expectation value).


derivator
 
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