practical MD-barostat question

[Toon]

Hi,

When performing an MD simulation, using the NPT_I ensemble with the
default settings and a target pressure of 1 bar, what is the order of
magnitude of the oscillations in the instantaneous pressure that one
should expect? (I have set PV_AVA to true in the input file to get the
instantaneous pressure in the output file.) Since I'm new on this
subject, I was performing a simple test run on a box of solid methane
with 64 molecules. (low temperature, below 90K, zero diffusion) I see
oscillations in the instantaneous pressure with an amplitude of 5000
bar. Is this normal? Maybe the answer is very system dependent?

best regards,

Toon