Hi LAMMPS users ,
I have a system with one C60 inside of about 1000 water molecules .
I want to run my simulation in the NPT ensemble and also I want to consider C60 as a rigid molecule .
first , I used this commands
…
fix 1 SPC shake 1.0e-4 500 1000 a 3 b 2
velocity all create 1.0 12345689 dist uniform
fix 2 C60 rigid/npt molecule temp 300.0 300.0 100.0 iso 1.0 1.0 1000.0
fix 3 SPC npt temp 300.0 300.0 100.0 iso 1.0 1.0 1000.0
…
with using of this command I could control pressure at around 1 atm , but later I understood this is error because there can only be one fix which monitors the global pressure and changes the simulation box dimensions , I also got an error " Non-numeric box dimensions - simulation unstable " after changing my LAMMPS version !
now I am using this command :
…
fix 1 SPC shake …
velocity all …
fix 2 SPC npt temp 300.0 300.0 100.0 iso 1.0 1.0 1000.0 dilate all
fix 3 C60 rigid/nvt molecule temp 300.0 300.0 100.0
…
and also I check this one :
…
fix 1 SPC shake …
velocity all …
fix 2 C60 rigid molecule
fix 3 SPC npt tem 300.0 300.0 100.0 iso 1.0 1.0 1000.0
…
At these two command Pressure has great fluctuation and actually I can not understand which one is suitable for my simulation ,I will be grateful if you can help me .
Do i need more study ? !!
Thanks for your attention .
Best ,
Saeed.