I've recently become interested in using Mesocite DPD to obtain structural information of conjugated polymers in various solvents.  Since these systems have quite rigid backbones, I am investigating the use of 3-body angle potentials for the backbone beads to simulate this rigidity.  My strategy has been to run atomistic dynamics on small oligomers of the polymers and obtain structural parameters like Rg and end-to-end distance from these runs.  Subsequently, I have taken these results and would like to devise bead angle-bending parameters for DPD that can reproduce the structure obtained in the atomistic runs on the olgomers.  I then plan to study the structures of higher molecular weight polymers with DPD.

After making some exploratory DPD runs with varying angle-bending parameters, I've noticed that I can tune the dynamical structural results by adjusting the angle parameters.  For example, I can move the peak of the end-to-end distance distribution to effectively match the atomistic results for the oligomers.  Unfortunately, what I cannot seem to match is the width of the distribution.  As you might expect, this width is a function of the energetic parameter i.e the greater the parameter, the narrower the distribution.

So, since I would like to match the peak as well as the width, I have started thinking about modifying the connected bead-bead stretch along with the angle parameters.  I realize that stiffer parameters require shorter timesteps.  Does anyone have any experience in this area, or thoughts about alternative strategies that can help?

Anthony