output pressure is not equal input pressure

Dear Lammps users and developers.

I am Tuan Ho from Geochemistry department, Sandia Labs

I am simulating water/CO2 system using TIP4P/2005 and rigid CO2 TRaPPE models.

I used fix nvt and fix shake for water and fix rigid/nvt/small for CO2. I used fix press/berendsen to control the pressure (please see the attached input file).

My problem is that the averaged output pressure is always around 1.5 times smaller than the input pressure.

(For the system that only has CO2, I got it right (input P = output P). I think there might be something wrong with the interaction between water/CO2 but cannot find it out.

Please let me know if you find any solution for this problem.

Tuan

Thanks in advanced.

equi.lammps (1.98 KB)

Dear Lammps users and developers.

I am Tuan Ho from Geochemistry department, Sandia Labs

I am simulating water/CO2 system using TIP4P/2005 and rigid CO2 TRaPPE models.

I used fix nvt and fix shake for water and fix rigid/nvt/small for CO2. I used fix press/berendsen to control the pressure (please see the attached input file).

My problem is that the averaged output pressure is always around 1.5 times smaller than the input pressure.

(For the system that only has CO2, I got it right (input P = output P). I think there might be something wrong with the interaction between water/CO2 but cannot find it out.

Please let me know if you find any solution for this problem.

Tuan

Thanks in advanced.

Thank you Ray

That pdamp works for my particular system. If I change pressure too fast my system will crash. I found a sily mistake over the weekend. It seems to work now.

Thank you very much.

Tuan