Dissipative particle dynamics electrostatics

Dear all,
I am using Mesocity DPD and my system containscharge beads. I created Forcefiled for the system and electrostatics was added from the interaction Forcefiled. I got that:

DPD calculation - Aborting dynamics.
An unphysical integration step (>100 Angstroms) has been detected.
Try relaxing the structure with geometry optimization, reducing the time step, 
reducing the temperature or a combination of these.

Then, I followe the steps from  example ( Coarse-grained molecular dynamics of a lipid bilayer) for the gemetry optimiztion to relaxing the structure 
I got: 
WARNING Convergence criteria are not satisfied. 
 Calculation did not reach convergence.

I colud not reach convergence.

My
questions:
1. How can I deal with charge system by using DPD?
2. If I need to do gemetry optimiztion how can I reach convergence?
3.For charge syetem, what is the best function form for Van Der Waals ( Soft Harmonic or LJ_12_6)?