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Abstract
<p class="first" id="d13978773e126">Smoothed dissipative particle dynamics (SDPD)
[P. Español and M. Revenga, Phys. Rev.
E
<b>67</b>, 026705 (2003)] is a thermodynamically consistent particle-based
continuum hydrodynamics solver that features scale-dependent thermal
fluctuations. We obtain a new formulation of this stochastic
method for ideal two-component mixtures through a discretization of the
advection-diffusion equation with thermal noise in the
concentration field. The resulting multicomponent approach is consistent with the
interpretation of the SDPD particles as moving volumes of fluid and reproduces the
correct fluctuations and diffusion dynamics. Subsequently, we provide a
general
<i>multiscale</i> multicomponent SDPD framework for
simulations of molecularly miscible systems spanning length scales from nanometers
to
the non-fluctuating continuum limit. This approach reproduces appropriate equilibrium
properties and is validated with simulation of simple one-dimensional diffusion across
multiple
length scales.
</p>
We demonstrate how an iterative method for potential inversion from distribution functions developed for simple liquid systems can be generalized to polymer systems. It uses the differences in the potentials of mean force between the distribution functions generated from a guessed potential and the true distribution functions to improve the effective potential successively. The optimization algorithm is very powerful: convergence is reached for every trial function in few iterations. As an extensive test case we coarse-grained an atomistic all-atom model of polyisoprene (PI) using a 13:1 reduction of the degrees of freedom. This procedure was performed for PI solutions as well as for a PI melt. Comparisons of the obtained force fields are drawn. They prove that it is not possible to use a single force field for different concentration regimes. Copyright 2003 Wiley Periodicals, Inc.