Tuesday, July 9, 2013

1307.2115 (Riccardo Chelli et al.)

Convective versus standard replica-exchange in ergodic regimes    [PDF]

Riccardo Chelli, Giorgio F. Signorini
In a recent article (J. Comput. Chem. 2013, 34, 132-140), an alternative approach to the standard even-odd transition scheme of replica-exchange (RE) method, called convective-RE, has been introduced. Tests on systems of varying complexity have shown that convective-RE may increase the number of replica round-trips in temperature space with respect to the standard exchange scheme, leading to a more effective sampling of energy basins. Moreover, it has been shown that the method may prevent the formation of bottlenecks in the diffusive walk of replicas through the space of temperature states. By using an ideal temperature-RE model and a classical harmonic-oscillator RE scheme, we show that, when ergodicity is not broken and convergence of the acceptance probabilities is attained, the round-trip ratio between convective and standard-RE is at maximum $\sim 1.5$ (a much smaller value than that observed in non-ergodic simulations), while the standard-RE actually outperforms convective-RE as the acceptance probabilities exceed a crossover regime dependent on the system. We also gain some evidence that, when a bottleneck is present, increasing the number of replicas may lead to acceptance probabilities for which benefits of convective-RE are lost.
View original: http://arxiv.org/abs/1307.2115

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