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Title: Diffusivity anomaly in modified Stillinger-Weber liquids
Authors: Sengupta, Shiladitya
Vasisht, Vishwas V.
Sastry, Srikanth
Keywords: Physical Chemistry
Atomic, Molecular & Chemical Physics
Universal Scaling Law
Configurational Entropy
Supercooled Silicon
Issue Date: 2014
Publisher: American Institute of Physics
Citation: Sengupta, S; Vasisht, VV; Sastry, S, Diffusivity anomaly in modified Stillinger-Weber liquids. Journal of Chemical Physics 2014, 140 (4), 44503
Journal of Chemical Physics
Abstract: By modifying the tetrahedrality (the strength of the three body interactions) in the well-known Stillinger-Weber model for silicon, we study the diffusivity of a series of model liquids as a function of tetrahedrality and temperature at fixed pressure. Previous work has shown that at constant temperature, the diffusivity exhibits a maximum as a function of tetrahedrality, which we refer to as the diffusivity anomaly, in analogy with the well-known anomaly in water upon variation of pressure at constant temperature. We explore to what extent the structural and thermodynamic changes accompanying changes in the interaction potential can help rationalize the diffusivity anomaly, by employing the Rosenfeld relation between diffusivity and the excess entropy (over the ideal gas reference value), and the pair correlation entropy, which provides an approximation to the excess entropy in terms of the pair correlation function. We find that in the modified Stillinger-Weber liquids, the Rosenfeld relation works well above the melting temperatures but exhibits deviations below, with the deviations becoming smaller for smaller tetrahedrality. Further we find that both the excess entropy and the pair correlation entropy at constant temperature go through maxima as a function of the tetrahedrality, thus demonstrating the close relationship between structural, thermodynamic, and dynamical anomalies in the modified Stillinger-Weber liquids. (C) 2014 AIP Publishing LLC.
Description: Restricted Access
ISSN: 0021-9606
Appears in Collections:Research Articles (Srikanth Sastry)

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