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Onsager Coefficients and Dynamic SCF Theory DSCFT

In order to describe the diffusive dynamics of composition fluctuations in binary mixtures one can extend the time-dependent Ginzburg-Landau methods to the free energy functional of the SCF theory. The approach relies on two ingredients a free energy functional that accurately describes the chemical potential of a spatially inhomogeneous composition distribution out of equilibrium and an Onsager coefficient that relates the variation of the chemical potential to the current of the composition. [Pg.38]

We implicitly assume that the out of equilibrium configuration can be described by the spatially varying composition but that we do not have to specify the details of the molecular conformations. This can be justified if the time scale on which the composition changes is much larger than the molecular relaxation time, such that the chain conformations are always in local equilibrium with the instantaneous composition. The time scale for the chain conformations to equilibrate is set by r = B-l/D, where D denotes the single chain self-diffusion constant. Moreover, we assume that the free energy obtained from the SCF theory also provides an accurate description even out of equilibrium, i.e., not close to a saddle point. [Pg.38]

one can relate the spatial variation of the chemical potential to a current of the composition. [Pg.38]

t) denotes the current density at position r at time t. There is only one independent chemical potential, because of the incompressibihty constraint and it is given by fj, = with 3 [ Pa from Eq. 53. [Pg.38]

The kinetic Onsager coefficient, A r, r ), relates the chemical force acting on a monomer at position r due to the gradient of the chemical potential to the concomitant cmrent density at position r. This describes pmely relax-ational dynamics, inertial effects are not captmed. can be modelled in [Pg.38]


See other pages where Onsager Coefficients and Dynamic SCF Theory DSCFT is mentioned: [Pg.38]    [Pg.38]   


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