title: How Well Can Coarse-Grained Models of Real Polymers Describe Their Structure? The Case of Polybutadiene.
abstract: Coarse-graining of chemical structure of macromolecules in the melt is investigated using extensive molecular dynamics simulation data which are based on a united atom force-field model of polybutadiene. Systematically increasing the number, n, of the united atoms approximated by an effective coarse-grained monomer, we study the influence of degree of coarse-graining on the structure functions such as the segment-segment intermolecular and intramolecular correlation functions. These results are compared to Monte Carlo simulations of the corresponding coarse-grained bead-spring model and Chen-Kreglewski potential for chain molecules. In contrast to the atomistic chemically realistic model of polybutadiene, the bending and torsional potentials are not included into the coarse-grained models. Nevertheless, for a range of intermediate values of n a good qualitative agreement between intra- and intermolecular coarse-grained correlations of the atomistic model and the coarse-grained bead-spring model is found on large and intermediate length scales, but deviations occur on length scales well below one nanometer. The structure functions obtained for the Chen-Kreglewski chains exhibit many artificial features.
authors.affiliation: Institut für Physik, WA 331, Johannes-Gutenberg Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany, and Institut für Theoretische Physik, Georg-August Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany.
authors.forename: Leonid
authors.initials: L
authors.lastname: Yelash
authors.affiliation: Institut für Physik, WA 331, Johannes-Gutenberg Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany, and Institut für Theoretische Physik, Georg-August Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Müller
authors.affiliation: Institut für Physik, WA 331, Johannes-Gutenberg Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany, and Institut für Theoretische Physik, Georg-August Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Paul
authors.affiliation: Institut für Physik, WA 331, Johannes-Gutenberg Universität Mainz, Staudingerweg 7, D-55099 Mainz, Germany, and Institut für Theoretische Physik, Georg-August Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany.
authors.forename: Kurt
authors.initials: K
authors.lastname: Binder