### Can such long time steps really be used in dissipative particle dynamics
simulations?

B. Hafskjold, C. C. Liew, and __W. Shinoda__

Mol. Simul. **30** 879-885 (2004).

Commonly used time steps in dissipative particle dynamics (DPD) simulations
are too large and lead to systematic errors in the computed properties.
The main source of errors is the inaccurate integration of the conservative
force. This error can to some extent be reduced by constructing a smoother
force without the abrupt change at the cut-off distance, but the improvement
is marginal. Alternative, smooth forces we have tried lead to the same
conclusion. It is possible to find combinations of parameters for the random
and dissipative forces that make errors cancel, but the combinations will
depend on the system's thermodynamic state and on the particular force
model. The only safe procedure is to use small time steps, *i.e.* comparable with those used in MD simulations. Alternatively, an improved
integration algorithm should be used for the conservative force.