##### dynamics of non-interacting point particles in 2D #####

variable        rng string gaussian
variable        seed string 198098
variable        temp string 5.0
variable        gamma_t string 1.0
variable        params string ${rng}_${temp}_${gamma_t}

units           lj
atom_style      atomic
dimension       2
newton off

lattice         sq 0.4
region          box block -30 30 -30 30 -0.2 0.2
create_box      1 box
create_atoms    1 box
mass            * 1.0
velocity        all create 1.0 1 loop geom

neighbor        1.0 bin
neigh_modify    every 1 delay 1 check yes

pair_style none

fix 1 all brownian ${temp} ${seed} rng ${rng} gamma_t ${gamma_t}


#initialisation for the main run

# MSD
compute         msd  all msd

thermo_style    custom step temp ke pe c_msd[*]

#dump            1 all custom 1000 dump_${params}_2d.lammpstrj id type &
#                x y z xu yu zu fx fy fz
#dump_modify     1 first yes sort id

timestep        0.00001
thermo          100

# main run
run             3000