[lammps-users] DPD simulation and Electrostatic interactions

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1

Dear All,

I want to simulate polyelectrolytes system with DPD package of LAMMPS. There are two papers for developing dpd method with Electrostatic interactions.

Title: Electrostatic interactions in dissipative particle dynamics using the Ewald sums
Author(s): Gonzalez-Melchor M, Mayoral E, Velazquez ME, et al.
Source: JOURNAL OF CHEMICAL PHYSICS Volume: 125 Issue: 22 Article Number: 224107 Published: DEC 14 2006

Title: Electrostatic interactions in dissipative particle dynamics-simulation of polyelectrolytes and anionic surfactants
Author(s): Groot, RD
Source: JOURNAL OF CHEMICAL PHYSICS Volume: 118 Issue: 24 Pages: 11265-11277 Published: JUN 22 2003

BUT, There are few papers which use DPD method whth electrostatic interactions. So, I want to know whether LAMMPS can integrate the DPD method with electrostateic interactions. What must I pay attention to when doing simulation in technique?

I hope some kind experts give me some advice. Thanks a million

2

If you use pair_style hybrid, you could use dpd and coul/long
or coul/cut together. So you should be able to do DPD with Coulombics.

Steve

3

thanks steve,

But, The problem in using the Ewald or PPPM method in DPD simulations is that electrostatic interactions between DPD particles are soft and atoms with opposite
charge form artificial clusters of ions.So, some papers [J. Chem. Phys. 125, 224107 2006] deal with it using a charge distribution on DPD particles, not a point charge.

So, if I use pair_style hybrid, how can I give a charge distribution? Are there substitutable method to deal with charge on paritcle?

Thanks

2008/5/30, Steve Plimpton <sjplimp@…24…>:

4

thanks steve,

But, The problem in using the Ewald or PPPM method in DPD
simulations is that electrostatic interactions between DPD particles
are soft and atoms with opposite charge form artificial clusters of
ions.So, some papers [J. Chem. Phys. 125, 224107 2006] deal with
it using a charge distribution on DPD particles, not a point charge.

So, if I use pair_style hybrid, how can I give a charge
distribution? Are there substitutable method to deal with charge on
paritcle?

wende,

the solution tou your problem is embarrasingly simple:
take your favorite editor and implement it.

cheers,
    axel.

5

All the charges in LAMMPS assume a point charge. If you want
to do PPPM on an extended charge, you'd need to code the
equations for that model into a pppm/extended class or something
like that.

Steve