High fluctuation during NPT (CONT)


I’m trying to get the thermal expansion of a carbon nanotube. First the system was stabilized using fix langevin and nve for 35,000 time steps (dt=0.0001 ps). After this point, I applied npt ensemble to equilibrate the system at 50 K and 0 bar but there’s a big fluctuation in the pressure and I want to get of it. I tried different Pdamp values (0.01-1) and I also tried the drag keyword in npt but I couldn’t reduce the fluctuations. I’m attaching the figures in the ppt file that show the pressure and total energy behavior during the Langevin fix and npt. Any help to solve this problem would be appreciated. The code I used is copied below.

Fluctuation.pptx (228 KB)