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Re: [lammps-users] Questions about using fix rigid/small with dpd+srp in a nanocomposite system
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Re: [lammps-users] Questions about using fix rigid/small with dpd+srp in a nanocomposite system


From: Andrew Jewett <jewett.aij@...24...>
Date: Tue, 4 Sep 2018 19:47:02 -0700



On Mon, Sep 3, 2018, 7:39 PM Steve Plimpton <sjplimp@...24...> wrote:
I'm CCing Tim Sirk, author of the SRP pair style.
First, what do you mean by pair srp is incompatible
with rigid bodies?  Do you get an error message,
does something blow up or not work, etc?

I don't know if this helps, but I noticed that the doc page to pair_style srp claims that it does not work with rigid body integrators.

https://lammps.sandia.gov/doc/pair_srp.html

(Perhaps Tim can clarify.  We were looking at pair stop and thinking of generating a version of pair_style srp that might be able to simulate membranes.  But then I got distracted and lazy and moved on.  Unfortunately, we do use rigid bodies a lot in our simulations, so this was a deal-breaker for us.)

Steve


On Sun, Aug 26, 2018 at 3:23 PM, Shensheng Chen <schen205@...3093...> wrote:
Hi LAMMPS,

I want to simulate an nanoparticle+polymer system using DPD,  the system contains small rigid particles (no bond inside each particle) and polymers, no bonds between polymers and particles. I want to capture the entanglements among the polymers by using the hybrid DPD+SRP pair style, for the particles I use fix rigid/small to make sure they move as rigid bodies.

However,in lammps the SRP pair style is incompatible with the fix rigid integrator. Is there anyway to fix this incompatible problem to simulate this nanocompsite systems? I'll appreciate if anyone can solve this problem.

The version of lammps I am using is lammps-patch_17Mar2017.

For your convenient, the script is posted as follow.

#DPD simulation for bulk polymerization with termination
units           lj
atom_style      molecular
boundary     p p p

#Geometry
read_data    linear_np001_p03.dat
lattice        fcc 3.0

group        polymer     type 1
group        solv      type 2
group        particle  type 3
group           mixture   type 1 2 3

#Interaction parameter setting
mass        * 1.0

pair_style hybrid dpd 1.0 1.0 12345 srp 0.8 * mid exclude no
comm_modify    mode single cutoff 8.0 vel yes

pair_coeff    * *    dpd 25   4.5 1.0
pair_coeff      1*3   4   none
pair_coeff      4 4 srp 100.0 0.8

bond_style    harmonic
bond_coeff      * 64 0.7
special_bonds    lj 1 1 1 extra 4

angle_style cosine
angle_coeff * 4.0


velocity    all create 1 8577 dist gaussian mom yes

#Integrator control
neighbor    0.3 bin
neigh_modify    every 1 delay 5 check no
timestep        0.02


best,
shensheng

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