Dear all,
Trying to create an orthogonal box with atomic walls with fixed temperature.
using appropriate solid density and keeping walls temperature less than melting point.
but the wall does not remains fixed as I wish while time integration. (following is the input file)
How to create a perfect solid atomic wall with constant temperature.
Dear all,
Trying to create an orthogonal box with atomic walls with fixed temperature.
using appropriate solid density and keeping walls temperature less than
melting point.but the wall does not remains fixed as I wish while time integration.
(following is the input file)
why should it?
there is nothing in the input that would keep the particles from
relaxing into a lower potential energy and pick up kinetic energy in
the process.
How to create a perfect solid atomic wall with constant temperature.
if you want particles to move but stay around a fixed average
position, you can use fix spring/self
axel.
Thanks Axel,
Problem resolved.
Glad you got this working.
Just a quick comment:
LAMMPS is nice because it offers you a few ways to do this.
You can also immobilize ordinary atoms by omitting them from the
group of atoms whose equations of motion are being integrated. (In
other words, don't use "fix 1 all nvt ...").
There is an example of this online. First here is the picture:
http://www.moltemplate.org/images/translocation/walls+solvent+polymer_t=0.jpg
The "wall" atoms (purple) belong to group named "groupB".
The remaining atoms belong to the group named "mobile"
So I use "fix 1 mobile nvt ...". Here is the full input script:
http://www.moltemplate.org/examples/translocation/run.in.nvt
(comments:Ignore the line in this file which says "compute pressMobile
all pressure tempMobile". Sorry, I need to remove that line. You can
also probably disregard the line above it too, if the number of atoms
in your simulation is much larger than the number of wall atoms. The
other files used to construct this example are in the same directory
as this file.)
There is a version of this input script which was designed to work
under conditions of constant pressure. (However I'm not sure it
works.) It is located here:
http://www.moltemplate.org/examples/translocation/run.in.npt
LAMMPS also has several "wall" commands.
http://lammps.sandia.gov/doc/fix_wall.html
(I did not check your script to see if you are using these already.)
The only drawback is that the fix wall commands do not give you
unlimited flexibility to control the force between the wall and the
mobile atoms in your simulation.
Cheers
Andrew