[lammps-users] direction in setforce command

Hi Sandip,

I think you should use these commands:

fix 1 left_atoms setforce 0.0 0.0 0.0
fix 2 left_atoms aveforce -1.0 0.0 0.0

fix 3 right_atoms setforce 0.0 0.0 0.0
fix 4 right_atoms aveforce 1.0 0.0 0.0

because the first command sets all forces on left atoms to zero and then
the second command applies the force to the group of atoms in such a way
that every atom experiences the same force.


Message: 1
Date: Fri, 29 Feb 2008 22:30:22 +0530
From: "Sandip Haldar" <[email protected]>
Subject: [lammps-users] direction in setforce command
To: <[email protected]>
  <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"

Hi all,
I needed little clarification of the command. If I use setforce to push
few atoms in which direction will they be pushed.

I have a domain X= -l to l with a hole at X=0. I want to push the right
side atoms to +X direction and left side atoms to -X direction. I am

fix 1 left_atoms setforce -1.0 0 0
fix 2 right_atoms setforce 1.0 0 0

Is this ok or there is any better command?
Thanks in advance,
Sandip Haldar

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Message: 2
Date: Fri, 29 Feb 2008 10:57:29 -0600
From: David Farrell <[email protected]>
Subject: [lammps-users] Parallel Replica Dynamics w/ LAMMPS?
To: LAMMPS user list <[email protected]>
Message-ID: <[email protected]>
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Hi All,

I am curious if anyone on the list has tried to set up a parallel
replica dynamics (accelerated MD method developed by Art Voter of LLNL
and coworkers) run using LAMMPS as a base. It is essentially running a
group of nearly identical simulations in parallel, with periodic
communications between them.

One of the things that is needed for PRD to work is a sort of
'wrapper' which will allow for the creation of the replicas and
starting the simulations, allow the replicas to communicate if a
transition has been detected in one of the replicas, and if so, to
stop all the others, then communicate the state of the replica that
had the transition to the other replicas(perhaps create some output),
and repeat the process.

Add added complexity will come in the fact that I will have to deal
with a batch scheduler system too, because I am using an HPC center

Anyone ever try anything like this?


David E. Farrell
Graduate Student
Mechanical Engineering
Northwestern University
email: [email protected]

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