Pressure fluctuations

I run a simulation for polymers chain. In fix npt I set external pressure to zero. I know that the pressure fluctuations in solids is natural, but I feel that this fluctuations is high. The unit is real. The pressure output in 500,000 steps is following:

The pressure fluctuation does not seem bad at all, especially it oscillates about zero. Magnitude of fluctuation decreases with increasing system size.


Thanks for your answer a lot. In your opinion the difference between 0 to 500 atm isn’t high? Then I deformed the cell and calculate stress, but the stress which is obtained in my simulation was 100 times than real value. I thought this is as result of pressure fluctuation.

Thanks a lot for your guide.