Hi,
I’d like to create a system containing molecules on which other molecules will be bounced back.
it’s like mobile reflecting wall.
Could anyone have an idea?
Thank you.
Hi,
I'd like to create a system containing molecules on which other molecules
will be bounced back.
huh?? what is this supposed to represent?
it's like mobile reflecting wall.
so why not have a moving reflecting wall instead?
axel.
Thank you.
Yes, I can use a moving reflecting wall.
But I am trying to make a moving reflecting particle of which movement depends simultaneously on other particles.
Okay, let’s think in this way:
if I use “fix wall/reflect” with “variable”, can I set xyz positions of a particular particle to the variable?
for example,
the particle consists of 4 atoms and this particle is not fixed.
time step 0
1 1.0 1.0 1.0 (atom #, x, y, z)
2 1.0 1.0 2.0
3 1.0 1.0 3.0
4 1.0 1.0 4.0
at this time step, reflecting wall position should be xlo 1.0 xhi 1.0 ylo 1.0 yhi 1.0 zlo 1.0 zhi 4.0.
time step 1
1 2.0 1.0 1.0 (atom #, x, y, z)
2 1.0 2.0 2.0
3 1.0 3.0 3.0
4 1.0 4.0 4.0
at this time step, reflecting wall position should be xlo 1.0 xhi 2.0 ylo 1.0 yhi 4.0 zlo 1.0 zhi 4.0.
Can I do this?
If so, could anyone let me know how to?
Thank you!!!
Thank you.
Yes, I can use a moving reflecting wall.
But I am trying to make a moving reflecting particle of which movement
depends simultaneously on other particles.
this is not a helpful explanation. you say _how_ you want to do it,
but not what it is supposed to _represent_.
Okay, let's think in this way:
if I use "fix wall/reflect" with "variable", can I set xyz positions of a
particular particle to the variable?
sure, you can set any atom coordinate to any xyz value using the
set command and instead of numbers you can use "equal" style
variables since those will be expanded before the command is evaluated.
for example,
the particle consists of 4 atoms and this particle is not fixed.
time step 0
1 1.0 1.0 1.0 (atom #, x, y, z)
2 1.0 1.0 2.0
3 1.0 1.0 3.0
4 1.0 1.0 4.0
at this time step, reflecting wall position should be xlo 1.0 xhi 1.0 ylo
1.0 yhi 1.0 zlo 1.0 zhi 4.0.
time step 1
1 2.0 1.0 1.0 (atom #, x, y, z)
2 1.0 2.0 2.0
3 1.0 3.0 3.0
4 1.0 4.0 4.0
at this time step, reflecting wall position should be xlo 1.0 xhi 2.0 ylo
1.0 yhi 4.0 zlo 1.0 zhi 4.0.
Can I do this?
by the very nature of reflection walls, you cannot restrict their "impact area".
proper reflection requires special treatment (ever read about MD with hard
spheres?) that is different from the typical soft potentials (or
walls) used in MD.
you have to project back in time the position of the reflection point and then
change the position and velocity of the reflected particle accordingly.
axel.
Why don’t you just make the reflecting particle interact via other constituents via a short-ranged, “steep” repulsive potential? Physics should be ~ the same.