Article

Residual multiparticle entropy does not generally change sign near freezing

Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712-0231, USA.
The Journal of Chemical Physics (Impact Factor: 3.12). 05/2008; 128(16):161101. DOI: 10.1063/1.2916697
Source: PubMed

ABSTRACT The residual multiparticle entropy (RMPE) of two- and three-dimensional fluids changes sign near the freezing line, providing a quasiuniversal "one-phase" rule for the location of the liquid-solid transition. We present new simulation results for d-dimensional hard-sphere fluids (d=1-5) which show, however, that this freezing criterion fails in other spatial dimensions. The results also call into question the idea that a change in sign of the RMPE implies the emergence of a new kind of local structural order in the fluid.

Full-text

Available from: Thomas Michael Truskett, Apr 26, 2015
0 Followers
 · 
74 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The relationships between diffusivity and the excess, pair and residual multiparticle contributions to the entropy are examined for Lennard-Jones liquids and binary glassformers, in the context of approximate inverse power law mappings of simple liquids. In the dense liquid where diffusivities are controlled by collisions and cage relaxations, Rosenfeld-type excess entropy scaling of diffu-sivities is found to hold for both crystallizing as well as vitrifying liquids. The crucial differences between the two categories of liquids emerge only when local cooperative effects in the dynamics result in significant caging effects in the time-dependent behaviour of the single-particle mean square displacement. In the case of glassformers, onset of such local cooperativity coincides with onset of deviations from Rosenfeld-type excess entropy scaling of diffusivities and increasing spatiotemporal heterogeneity. In contrast, for two-and three-dimensional liquids with a propensity to crystallise, the onset of local cooperative dynamics is sufficient to trigger crystallization provided that the liquid is sufficiently supercooled that the free energy barrier to nucleation of the solid phase is negligible. The state points corresponding to onset of transient caging effects can be associated with typical values, within reasonable bounds, of the excess, pair, and residual multiparticle entropy as a consequence of the isomorph-invariant character of the excess entropy, diffusivity and related static and dynamic correlation functions. © 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4731705]
    The Journal of Chemical Physics 07/2012; 137(2). DOI:10.1063/1.4731705 · 3.12 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A coarse-grained system of one-dimensional (1D) hard spheres (HSs) is created using the Delaunay tessellation, which enables one to define the quasi-0D state. It is found from comparing the quasi-0D and 1D free energy densities that a frozen state due to the emergence of quasi-0D HSs is thermodynamically more favorable than fluidity with a large-scale heterogeneity above crossover volume fraction of ϕc=e/(1+e)=0.731⋯ϕc=e/(1+e)=0.731⋯ , at which the total entropy of the 1D state vanishes. The Delaunay-based lattice mapping further provides a similarity between the dense HS system above ϕcϕc and the jamming limit in the car parking problem.
    Physics Letters A 05/2014; 378(26-27). DOI:10.1016/j.physleta.2014.04.066 · 1.63 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We present grand canonical transition-matrix Monte Carlo (GC-TMMC) as an efficient method for simulating gas adsorption processes, with particular emphasis on subcritical gas adsorption in which capillary phase transitions are present. As in other applications of TMMC, the goal of the simulation is to compute a particle number probability distribution (PNPD), from which thermophysical properties of the system can be computed. The key advantage of GC-TMMC is that, by appropriate use of histogram reweighting, one can generate an entire adsorption isotherm, including those with hysteresis loops, from the PNPD generated by a single GC-TMMC simulation. We discuss how to determine various thermophysical properties of an adsorptive system from the PNPD, including the identification of capillary phases and capillary phase transitions, the equilibrium phase transition, other free energies, and the heat of adsorption. To demonstrate the utility of GC-TMMC for studies of adsorption, we apply the method to various systems including cylindrical pores and a crystalline adsorbent to compute various properties and compare results to previously published data. Our results demonstrate that the GC-TMMC method efficiently yields adsorption isotherms and high-quality properties of adsorptive systems and can be straightforwardly applied to more complex fluids and adsorbent materials.
    The Journal of Physical Chemistry C 03/2013; 117(11):5861–5872. DOI:10.1021/jp400480q · 4.84 Impact Factor