The solvent-accessible surface area (SASA) for coarse-grained and atomistic fragments was calculated, to compare their molecular shape. This was done with the GROMACS tool gmx sasa, using 4800 dots per sphere and a probe radius of 0.191 nm for atomistic and coarsegrained fragments. The van der Waals radii from the work of Roland and Taylor were used for calculating the SASA of the atomistic fragments. In the case of the coarsegrained fragments, radii were chosen according to the bead sizes. It should be noted that, due to using the united atom representation of the GROMOS force field, experimentally determined radii were not available for the united atoms, which represent the CH 1 , CH 2 , and CH 3 groups. Instead, they were approximated using that of a single carbon atom. To provide other reference values for the SASA, values with van der Waals radii from GROMOS and from the mapped molecules were also calculated (see Figure ). Furthermore, the radius of gyration (R g ) was compared to the atomistic reference as a measure of the extent of a fragment, using the GROMACS tool gmx gyrate. For each fragment, both properties (R g and SASA) were determined firstly from the atomistic reference trajectories of isolated fragments and secondly for the coarse-grained representation, using the trajectory with the converged model, which was part of the Swarm-CG parametrization. The time averages and corresponding standard deviations were determined from time evolutions using gmx analyze. This was done in the same way for other quantities used in this research, that are connected to a time evolution, for example the SASA, densities, and distributions of bonded interactions, all of which are discussed later.