Pressure not getting equilibrated to desired value

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1

I am doing simulation of alumina atoms. I want to get the desired temp of 300 K and 1 bar pressure.

Temperature is reaching the desired value of 300 K but pressure is sometimes very positive (2000 bar) or sometimes too negative (-3000 bar) I tried with different Pdamp values of 10, 100 but not getting the required pressure.

timestep 0.005 # picoseconds
velocity all create 300 102486 mom yes rot yes dist gaussian

fix 1 all npt temp 300 300 1.0 iso 1.0 1.0 10.0
run 30000

2

Are those mean pressure that you’re reporting? Because pressure can wildly fluctuate, specially in an incompressible system.

3

Also take a look at this thread where Axel has clearly explained the reasons.