On the determination of the crystalvapor surface free energy, and why a Gaussian expression can be accurate for a system far from Gaussian
Abstract
The crystalvapor surface free energy γ is an important physical parameter governing physical processes, such as wetting and adhesion. We explore exact and approximate routes to calculate γ based on cleaving an intact crystal into noninteracting subsystems with crystalvapor interfaces. We do this by turning off the interactions, ΔV, between the subsystems. Using the softcore scheme for turning off ΔV, we find that the free energy varies smoothly with the coupling parameter λ, and a single thermodynamic integration yields the exact γ. We generate another exact method, and a cumulant expansion for γ by expressing the surface free energy in terms of an average of e{sup −βΔV} in the intact crystal. The second cumulant, or Gaussian approximation for γ is surprisingly accurate in most situations, even though we find that the underlying probability distribution for ΔV is clearly not Gaussian. We account for this fact by developing a nonGaussian theory for γ and find that the difference between the nonGaussian and Gaussian expressions for γ consist of terms that are negligible in many situations. Exact and approximate methods are applied to the (111) surface of a LennardJones crystal and are also tested for more complex molecular solids, the surface ofmore »
 Authors:
 Department of Chemical and Biomolecular Engineering, Ohio State University, Columbus, Ohio 43210 (United States)
 (United States)
 Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210 (United States)
 Publication Date:
 OSTI Identifier:
 22678973
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Chemical Physics; Journal Volume: 145; Journal Issue: 5; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ADHESION; APPROXIMATIONS; COUPLING; CRYSTALS; DISTRIBUTION; ELECTRONS; EXPANSION; FREE ENERGY; FREEZING; INTERACTIONS; OCTANE; PROBABILITY; SOLIDS; SURFACES; THERMODYNAMICS
Citation Formats
Modak, Viraj P., Email: virajmodak@gmail.com, Wyslouzil, Barbara E., Email: wyslouzil.1@osu.edu, Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210, and Singer, Sherwin J., Email: singer@chemistry.ohiostate.edu. On the determination of the crystalvapor surface free energy, and why a Gaussian expression can be accurate for a system far from Gaussian. United States: N. p., 2016.
Web. doi:10.1063/1.4959167.
Modak, Viraj P., Email: virajmodak@gmail.com, Wyslouzil, Barbara E., Email: wyslouzil.1@osu.edu, Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210, & Singer, Sherwin J., Email: singer@chemistry.ohiostate.edu. On the determination of the crystalvapor surface free energy, and why a Gaussian expression can be accurate for a system far from Gaussian. United States. doi:10.1063/1.4959167.
Modak, Viraj P., Email: virajmodak@gmail.com, Wyslouzil, Barbara E., Email: wyslouzil.1@osu.edu, Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210, and Singer, Sherwin J., Email: singer@chemistry.ohiostate.edu. Sun .
"On the determination of the crystalvapor surface free energy, and why a Gaussian expression can be accurate for a system far from Gaussian". United States.
doi:10.1063/1.4959167.
@article{osti_22678973,
title = {On the determination of the crystalvapor surface free energy, and why a Gaussian expression can be accurate for a system far from Gaussian},
author = {Modak, Viraj P., Email: virajmodak@gmail.com and Wyslouzil, Barbara E., Email: wyslouzil.1@osu.edu and Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210 and Singer, Sherwin J., Email: singer@chemistry.ohiostate.edu},
abstractNote = {The crystalvapor surface free energy γ is an important physical parameter governing physical processes, such as wetting and adhesion. We explore exact and approximate routes to calculate γ based on cleaving an intact crystal into noninteracting subsystems with crystalvapor interfaces. We do this by turning off the interactions, ΔV, between the subsystems. Using the softcore scheme for turning off ΔV, we find that the free energy varies smoothly with the coupling parameter λ, and a single thermodynamic integration yields the exact γ. We generate another exact method, and a cumulant expansion for γ by expressing the surface free energy in terms of an average of e{sup −βΔV} in the intact crystal. The second cumulant, or Gaussian approximation for γ is surprisingly accurate in most situations, even though we find that the underlying probability distribution for ΔV is clearly not Gaussian. We account for this fact by developing a nonGaussian theory for γ and find that the difference between the nonGaussian and Gaussian expressions for γ consist of terms that are negligible in many situations. Exact and approximate methods are applied to the (111) surface of a LennardJones crystal and are also tested for more complex molecular solids, the surface of octane and nonadecane. Alkane surfaces were chosen for study because their crystalvapor surface free energy has been of particular interest for understanding surface freezing in these systems.},
doi = {10.1063/1.4959167},
journal = {Journal of Chemical Physics},
number = 5,
volume = 145,
place = {United States},
year = {Sun Aug 07 00:00:00 EDT 2016},
month = {Sun Aug 07 00:00:00 EDT 2016}
}

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