  We examine the performance of various commonly used integration schemes in
dissipative particle dynamics simulations. We consider this issue using three
different model systems, which characterize a variety of different conditions
often studied in simulations. Specifically we clarify the performance of
integration schemes in hybrid models, which combine microscopic and meso-scale
descriptions of different particles using both soft and hard interactions. We
find that in all three model systems many commonly used integrators may give
rise to surprisingly pronounced artifacts in physical observables such as the
radial distribution function, the compressibility, and the tracer diffusion
coefficient. The artifacts are found to be strongest in systems, where
interparticle interactions are soft and predominated by random and dissipative
forces, while in systems governed by conservative interactions the artifacts
are weaker. Our results suggest that the quality of any integration scheme
employed is crucial in all cases where the role of random and dissipative
forces is important, including hybrid models where the solvent is described in
terms of soft potentials.
