Dynamics of Nucleation in the Ising Model.pdfVIP

Dynamics of Nucleation in the Ising Model Albert C. Pan and David Chandler Department of Chemistry, University of California, Berkeley, CA 94720-1460 (Dated: February 2, 2008) 4 0 Reactive pathways to nucleation in a three-dimensional Ising model at 60% of the critical temper- 0 ature are studied using transition path sampling of single spin flip Monte Carlo dynamics. Analysis 2 of the transition state ensemble (TSE) indicates that the critical nuclei are rough and anisotropic. The TSE, projected onto the free energy surface characterized by cluster size, N , and surface area, g u S , indicates the significance of other variables in addition to these two traditional reaction coordi- nates for nucleation. The transmission coefficient, κ, along N is κ ≈ 0.35, and this reduction of the A transmission coefficient from unity is explained in terms of the stochastic nature of the dynamic 3 model. 1 ] I. INTRODUCTION ical nucleus, then sits atop this free energy barrier be- h tween the undercooled and stable phases. This picture is c This paper presents a new application of transition found in any theory that relates the nucleus size to a sin- e m path sampling[1, 2, 3, 4], namely to nucleation of bulk gle reaction coordinate. In general, nucleation, as with - phase transitions[5]. It should be of interest to those all non-equilibrium process, can involve many