  We analyzed extensively the dynamics of polymer chains in solutions simulated
with dissipative particle dynamics (DPD), with a special focus on the potential
influence of a low Schmidt number of a typical DPD fluid on the simulated
polymer dynamics. It has been argued that a low Schmidt number in a DPD fluid
can lead to underdevelopment of the hydrodynamic interaction in polymer
solutions. Our analyses reveal that equilibrium polymer dynamics in dilute
solution, under a typical DPD simulation conditions, obey the Zimm model very
well. With a further reduction in the Schmidt number, a deviation from the Zimm
model to the Rouse model is observed. This implies that the hydrodynamic
interaction between monomers is reasonably developed under typical conditions
of a DPD simulation. Only when the Schmidt number is further reduced, the
hydrodynamic interaction within the chains becomes underdeveloped. The
screening of the hydrodynamic interaction and the excluded volume interaction
as the polymer volume fraction is increased are well reproduced by the DPD
simulations. The use of soft interaction between polymer beads and a low
Schmidt number do not produce noticeable problems for the simulated dynamics at
high concentrations, except that the entanglement effect which is not captured
in the simulations.
