How to mimic a charge cloud for DPD soft beads ?

Hi forum enthusiasts,

I am curious to simulate electrostatic interactions with DPD particles whose charges are smeared exponentially around the center. This potentially avoids nonphysical ionic pairs formation due to soft-core DPD interactions.

In the thread : http://lammps.sandia.gov/threads/msg17962.html
it is stated that charges are smeared in PPPM method, but this might be different from what the original poster was looking for.

Ewald sum formulation must fundamentally change to account for this charge cloud. To circumvent this obstacle, using a combination of " fix nve/limit " and DPD potential might be helpful.

I appreciate any confirmation on this idea and/or any alternative Lammps ability to mimic smeared charges appropriately.

Thanks,
Abouzar

Hi forum enthusiasts,

I am curious to simulate electrostatic interactions with DPD particles whose
charges are smeared exponentially around the center. This potentially avoids
nonphysical ionic pairs formation due to soft-core DPD interactions.

In the thread : http://lammps.sandia.gov/threads/msg17962.html
it is stated that charges are smeared in PPPM method, but this might be
different from what the original poster was looking for.

Ewald sum formulation must fundamentally change to account for this charge
cloud. To circumvent this obstacle, using a combination of " fix nve/limit "
and DPD potential might be helpful.

ewald sum or anything similar won't help. it still models point
charges. the "smearing" is part of the "trick" how you turn a single
slowly converging and conditionally convergent sum into two rapidly
converging sums to include the long-range nature of charges.

I appreciate any confirmation on this idea and/or any alternative Lammps
ability to mimic smeared charges appropriately.

not sure if this can be translated to DPD, but a former colleague of
mine implemented a couple of pair styles in order to address the same
problem you mention for implicit solvent calculations.

please have a look at the gauss/cut and coul/diel pair styles and have
a look at the papers by Lenart and Jusufi mentioned on the following
pages of the LAMMPS documentation.
http://lammps.sandia.gov/doc/pair_gauss.html
http://lammps.sandia.gov/doc/pair_coul_diel.html

axel.