Dear LAMMPS users
I am using LAMMPS to study water-methanol mixture.
I am trying to use NPT to equilibrate the system, and I find something not normal.
The system consists 600 Tip4p/2005 water and 85 methanol molecules.
If I use NPT with isotropic barostat (Nose-Hoover), the system is fine.
But when I use anisotropic barostat (Nose-Hoover), the volume fluctuates very widely.
I played with drag factor, relaxation time, and reduced time step, but they are not solving the widely fluctuation of volume.
I did the same run for pure methanol and water, and isotrobic and anisotropic barostat deliver similar results.
I am wondering is this because the dipole moment of methanol and water molecule is not the same?
I attach my input file for you guys to check
in.tip4p-300k-pre (2.46 KB)
Tip4p_MeOH_20wt.data (247 KB)