title: On the use of excess entropy scaling to describe single-molecule and collective dynamic properties of hydrocarbon isomer fluids.
abstract: We use molecular simulation to study the ability of excess entropy scaling relationships to describe the kinetic properties of four hydrocarbon isomers: n-octane, 2,2-dimethylhexane, 2,5-dimethylhexane, and 3-methyl-3-ethylpentane. Four dynamic properties are considered: translational and rotational diffusivities, a characteristic relaxation time for rotational motion, and a collective relaxation time stemming from analysis of the coherent intermediate scattering function. For each of the dynamic properties considered, reduced data collapse onto a species-specific common curve when expressed as a function of the thermodynamic excess entropy. Because each isomer exhibits a quantitatively distinct excess entropy scaling relationship, straightforward corresponding states principles do not provide an effective means to predict dynamic properties.
authors.affiliation: Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.
authors.forename: Ravi
authors.initials: R
authors.lastname: Chopra
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Truskett
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Errington
mesh_terms: D006586:Hexanes / Q000737:chemistry*; D007536:Isomerism; D009795:Octanes / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D006586:Hexanes; D009795:Octanes; C026728:octane