I am doing some calculations on the properties of alkanes. In my NPT run, the condition is set to 300K, 0Pa, using the Nose-Hoover thermostat. The simulation was run for 200,000 steps with a step size of 1 fs. The pressure was obtained by averaging the last 100,000 steps, the standard deviation of it was about 600 at.!
Besides, in my NVE+langevin runs, the pressure as well as the all its tensors also show significant fluctuation! I would like to know, if this is normal? Or how can I make the fluctuation smaller? I searched previous archives, but did not get enough information on this.
Thanks a lot.