Input Script help


units metal
atom_style atomic
dimension 3
boundary p p p

read data

replicate 1 1 1
pair_style hybrid airebo 3.0 lj/cut 5

mass 1 12.0107
mass 2 6.941
#mass 3 2.016

#group C type 1
#group Li type 2
#group H2 type 3

H2 Case

pair_coeff * * airebo CH.airebo C NULL # C-C
pair_coeff 2 2 lj/cut 0 0 # Li-Li
#pair_coeff 2 2 lj/cut 0.04886 2.728 # Li-Li
#pair_coeff 2 2 lj/cut 0.04886 2.728 # Li-Li
pair_coeff 1 2 lj/cut 0 0 # C-Li
#pair_coeff 1 2 lj/cut 0.05089 1.6 # C-Li
#pair_coeff 1 2 lj/cut 0.01089 3.064 # C-Li
pair_coeff 1 3 lj/cut 0.003795 3.194 # C-H2
pair_coeff 2 3 lj/cut 0.1338 1.97 # Li-H2
pair_coeff 3 3 lj/cut 0.00016 3.17 # H2-H2

Output Settings

thermo_style custom step etotal pe temp lx vol press
thermo 100

Output Settings

dump d1 all custom 100 cfg/run.*.xyz element x y z
dump_modify d1 element C Li H2

Check equilibration settings

variable Energy equal etotal
variable Temperature equal temp
variable Pressure equal press
fix ces all ave/time 1 100 100 v_Energy v_Temperature v_Pressure file out_energy.txt
System: Carbon Nanotubes doped with Lithium (Lithium atoms are at the center of hexagon of the Carbon Nanotubes)

In the above code, the pressure of the system is around 20686.534 bars. I would like to bring down the pressure to 0 bars, considering that there is no interaction between Lithium-Lithium and Lithium-Carbon (because I could not find the LJ parameters for Lithium-Carbon and Lithium-Lithium). The pressure of the system can be brought to 0 bars with press/berendsen fix but the lithium atoms are located in such a way that the lithium atoms in between the hexagon of the carbon nanotubes.

can you please suggest which fix must be used to get the pressure to 0 bars, such that, if the carbon atoms move simultaneously the lithium atoms must also move.

Despite the name “fix” there is no ‘magic’ fix command that can turn a bad model with bad parameters into a good one.

I seriously doubt that you can do a meaningful simulation of such a system with a classical model. Even using DFT would be tricky for this to get right.