Poisson's Ratio and Young's Modulus of Lipid Bilayers in Different Phases.
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As an example for the coarse grained lipid model introduced by Lenz and Schmid, we calculate the Poisson's ratio in the gel, fluid, and interdigitated phases.Having the Poisson's ratio, enable us to obtain the Young's modulus for the membranes in different phases.The approach may be applied to other membranes such as graphene and tethered membranes in order to predict the temperature dependence of its Poisson's ratio and Young's modulus.
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Affiliation: Department of Physics, University of Osnabrück , Osnabrück , Germany.
ABSTRACT
A general computational method is introduced to estimate the Poisson's ratio for membranes with small thickness. In this method, the Poisson's ratio is calculated by utilizing a rescaling of inter-particle distances in one lateral direction under periodic boundary conditions. As an example for the coarse grained lipid model introduced by Lenz and Schmid, we calculate the Poisson's ratio in the gel, fluid, and interdigitated phases. Having the Poisson's ratio, enable us to obtain the Young's modulus for the membranes in different phases. The approach may be applied to other membranes such as graphene and tethered membranes in order to predict the temperature dependence of its Poisson's ratio and Young's modulus. No MeSH data available. Related in: MedlinePlus |
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Mentions: To determine both E and ν, we need to determine one of these elastic constants separately. Utilizing the periodic boundary conditions, we introduce a method to compute the Poisson’s ratio for the surface (Abedpour et al., 2010). The Poisson’s ratio is the negative ratio of the transverse strain changes divided by the axial strain changes in a body when it is stretched or compressed along the axial direction under the tension below the proportional limit. For the infinitesimal diagonal strains, the Poisson’s ratio can be replaced by the ratio of the relative length changes as νij = −ΔLi/ηjLi, where ηj ≡ ΔLj/Lj is defined as the fraction of the axial length change. Here i ≠ j and i = x, y, and z. In the method, we present here the length between neighboring lipids is rescaled by a factor of (1 + η) in axial direction, let say y-direction, and the subsequent change of the simulation box size in perpendicular directions, in this case x- and z-direction, are monitored. While keeping the rescaled box length (1 + η) Ly constant, for fixing the pressure in the simulations, the box dimensions are now allowed to fluctuate in only the x- and z-directions. When the initial mean lengths in x and z-direction were Lx and Lz, new mean values of Lx + ΔLx and Lz + ΔLz are reached after rescaling, by re-equilibrating the system for a few number of MC steps, see Figure 3. |
View Article: PubMed Central - PubMed
Affiliation: Department of Physics, University of Osnabrück , Osnabrück , Germany.
No MeSH data available.