# Comment on"Elucidating the Mechanism of Nucleation near the Gas-Liquid Spinodal" [electronic resource].

- Published:
- Berkeley, Calif. : Lawrence Berkeley National Laboratory, 2008.

Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy. - Physical Description:
- 1 : digital, PDF file
- Additional Creators:
- Lawrence Berkeley National Laboratory and United States. Department of Energy. Office of Scientific and Technical Information

##### Access Online

- Restrictions on Access:
- Free-to-read Unrestricted online access
- Summary:
- In a recent Letter [1], Bhimalapuram, Chakrabarty and Bagchi (BCB) study the phase transformation mechanism of the Lennard-Jones fluid and the non-conserved Ising model. They compute the free energy as a function of the size of the largest droplet of the stable phase. In apparent contradiction to classical nucleation theory (CNT), they find that in both systems the free energy develops a minimum at subcritical cluster sizes. In this Comment we argue that this minimum is specific to the chosen order parameter, and that the observed behavior is in fact consistent with CNT. CNT states that the free energy F(N) of a single cluster of size N is a concave function with a maximum at the critical nucleus size N{sub c}. BCB, on the other hand, calculate the probability distribution of N*, the size of the largest cluster in the system, and compute the free energy βF*(N*) = -ln P(N*), where β = 1/k{sub B}T. This order parameter does not measure the size of a single cluster. Instead, when sampling small values of N*, one measures the statistical weight of configurations in which all clusters are at most N* in size. Hence a free energy penalty is incurred when one constrains N* to values smaller than the largest average cluster in the simulation volume V. It is this penalty that causes the sudden increase of F* as N* → 0 and the minimum at intermediate values of N*. We now illustrate how F(N) can be calculated from simulations. Our argument is intuitive but not exact, a formal derivation that yields an equivalent result can be found in Ref. 2. We choose the Ising model for concreteness. We aim to compute the probability that a given cluster has size N, where we imagine the center of the cluster to be fixed at site i. To simplify the calculation we consider clusters that overlap with site i, and correct for the N-fold translational degeneracy in a second step.
- Report Numbers:
- E 1.99:lbnl-527e

lbnl-527e - Note:
- Published through SciTech Connect.

06/18/2008.

"lbnl-527e"

Physical Review Letters ISSN 0031-9007; PRLTAO FT

Maibaum, Lutz.

Chemical Sciences Division - Funding Information:
- DE-AC02-05CH11231

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