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Chemistry

Craig J. Eckhardt Publications

1997

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Langmuir Monolayers As Disordered Solids: Strain-State Calculations Applied To Stearic Acid, David R. Swanson, Tadeusz Luty, Craig J. Eckhardt Sep 1997

Langmuir Monolayers As Disordered Solids: Strain-State Calculations Applied To Stearic Acid, David R. Swanson, Tadeusz Luty, Craig J. Eckhardt

Craig J. Eckhardt Publications

This paper presents a calculational procedure to determine the equilibrium phase for a given surface pressure π. The monolayer is treated as orientationally free tails grafted to a two-dimensional net formed by the head groups of the amphiphilic molecules. The head groups form a subsystem with translational degrees of freedom characterized by strain variables in the plane of the surface, and the tail groups compose a subsystem characterized by rotational degrees of freedom. The order in the monolayer derives indirectly from the crystalline head groups through translational–rotational coupling. A stress–strain relation is derived which shows the energetically most favorable path …


Monte Carlo Simulation Of The Solid To Superliquid Phase Transition Of Langmuir Monolayers. Ii. Characteristics Of Phase Transition, M.D. Gibson, D.R. Swanson, Craig J. Eckhardt, Xiao Cheng Zeng Feb 1997

Monte Carlo Simulation Of The Solid To Superliquid Phase Transition Of Langmuir Monolayers. Ii. Characteristics Of Phase Transition, M.D. Gibson, D.R. Swanson, Craig J. Eckhardt, Xiao Cheng Zeng

Craig J. Eckhardt Publications

The restricted-to-free rotator phase transition of fatty acid monolayers has been modeled using a potential which represents the amphiphiles as planar cross sections of fourfold symmetry. Using much larger system sizes than paper I [D. R. Swanson, R. J. Hardy, and C. J. Eckhardt, J. Chem. Phys. 99, 8194 (1993)], Monte Carlo simulations of the isobaric–isothermal ensemble of model systems with varied number of objects were undertaken to study the effect of system size on the characteristics and order of the phase transition. A peak in the specific heat vs temperature curve was observed near the transition. For each system …