[Zurück]

M. Montes Saralegui, A. Nikoubashman, G. Kahl:
"On the applicability of density dependent effective interactions in cluster-forming systems";
Journal of Chemical Physics, 146 (2017), 054904; S. ##.

We systematically studied the validity and transferability of the force-matching algorithm for com-
puting effective pair potentials in a system of dendritic polymers, i.e., a particular class of ultrasoft
colloids. We focused on amphiphilic dendrimers, macromolecules which can aggregate into clusters
of overlapping particles to minimize the contact area with the surrounding implicit solvent. Simu-
lations were performed for both the monomeric and coarse-grained models in the liquid phase at
densities ranging from infinite dilution up to values close to the freezing point. The effective pair
potentials for the coarse-grained simulations were computed from the monomeric simulations both
in the zero-density limit (Φ 0eff ) and at each investigated finite density (Φ eff ). Conducting the coarse-
grained simulations with Φ 0eff at higher densities is not appropriate as they failed at reproducing the
structural properties of the monomeric simulations. In contrast, we found excellent agreement between
the spatial dendrimer distributions obtained from the coarse-grained simulations with Φ eff and the
microscopically detailed simulations at low densities, where the macromolecules were distributed
homogeneously in the system. However, the reliability of the coarse-grained simulations deteriorated
significantly as the density was increased further and the cluster occupation became more polydis-
perse. Under these conditions, the effective pair potential of the coarse-grained model can no longer
be computed by averaging over the whole system, but the local density needs to be taken into account
instead.

http://dx.doi.org/10.1063/1.4975164