I have a problem in simulating isolated MWCNT(multi-walled carbon nanotube) under hydrostatic pressure. However, if I use the fix/npt command, which need the period boundary conditions, to control the pressure, the volume will decrease with the increasing hydrostatic pressure and result in a MWCNT bundles. In other words, the simulation is not isolated MWCNT any more. So I want to use the command fix/npt or some other command to control the pressure and at the same time exclude the effects of other boxs due to the period boundary conditions. Or other methods will be accepted if anyone have better suggestion. For example, can one control the pressure at a free boundary?
I had tried a lot and been in trouble for long time. Hope someone can help me! Sincerely thanks!
Dear all,
I have a problem in simulating isolated MWCNT(multi-walled carbon nanotube)
under hydrostatic pressure. However, if I use the fix/npt command, which
need the period boundary conditions, to control the pressure, the volume
will decrease with the increasing hydrostatic pressure and result in a MWCNT
bundles. In other words, the simulation is not isolated MWCNT any more. So I
want to use the command fix/npt or some other command to control the
pressure and at the same time exclude the effects of other boxs due to the
period boundary conditions. Or other methods will be accepted if anyone have
this makes no sense at all.
better suggestion. For example, can one control the pressure at a free
boundary?
there is no pressure control with a free boundary, since that is the
very definition of a free boundary. if you want a non-periodic system
*with* a boundary, you have to use walls.
I had tried a lot and been in trouble for long time. Hope someone can help
me! Sincerely thanks!
it seems to be that your problem is not the settings in LAMMPS but the
concept of your simulation: where is the hydrostatic pressure coming
from? it only can come from the medium in between the nanotubes. thus
you would apply force/pressure to that medium and thus the entire
system. however, this does not mean that the nanotubes may not
cluster. their clustering or not depends on their solubility in that
medium. you didn't say which medium you are using, so it is difficult
to make any specific comments here. but i don't see how there would be
a principal problem to run with periodic boundaries.