Is it possible to update the atoms in a group during a simulation?

LAMMPS LAMMPS Mailing List Mirror
1

Dear all,

I am running a large simulation, where I want to keep track of certain particles entering a particular region. The region is cubic, so that I can pick the molecules using a simple check on x, y & z coordinates.

I want to have the velocity, and angular velocities of those particles that are within the region. If I print the velocity and angular velocities of all the particles, the file size would be extremely big. Hence, I want to selectively print those particles that are within the region in that timestep.

I tried using variable, created a group using variable, and dumped the group:

variable findCavityAtoms atom “x > xlo && x < xhi”
group cavity variable findCavityAtoms
dump 1 cavity custom 1000 cav.data x y z vx vy vz

But the group is not updated every step.

Is it possible to do it? If so, could anybody point me in the right direction?

Thanking you,

Saikat Banerjee

2

Groups are fixed for the duration of a simulation.

You can, however, achieve what you want by defining a region which covers your volume of interest, then passing it to dump_modify region ( http://lammps.sandia.gov/doc/dump_modify.html).

3

Hi,

Thanks. It was a great help.

Saikat