Thank you very much for your response. I'm sorry my question was not
The axis of the cylinder is along the x-axis. The y- and z-axes (the
circumference) of the cylinder are non periodic, but the faces of the
cylinder may be periodic, if I am considering an infinitely long cylinder.
The pressure that I am looking to keep constant is that of the silicon atoms
on the inside "walls" of the cylinder.
i don't understand this. if this is supposed to be a nano object,
there is no physical reason to limit its expansion or contraction. it
will equilibrate and that is that.
The theory behind the simulation is that eventually the volume will
oscillate around an average value. I ran an nph simulation with a barostat,
and the resultant volume vs. time graph was a lovely exponential decay,
easily fitted. However, I had the boundaries set to be periodic, and I did
periodicity would not be a problem for as long as there is sufficient
distance between the images of the cylinders, so they don't interact.
not fix the circumference of the cylinder, which is necessary for a nanotube
here i disagree completely. why should there be a need to immobilize
the circumference of that cylinder. if that object cannot maintain its
structure, then you have a bigger problem. forcing it to be in a
specific geometry will only hide that problem.
With the nve simulation, I was able to have the correct boundary and
constraints, but the resulting volume is monotonically increasing, and I
have lost the fixed pressure.
i don't understand what you are trying to say here at all. again, this
hints at something else being out of whack. e.g. a bad structure, a
bad choice of potential or simulation parameters.
and overall, this is still far to vague for anything more specific.