# This is LAMMPS input script specifies a simple DPD simulation.
# It reproduces Fig. 2 of Groot and Warren, J. Chem. Phys. 107,
# 4423 (1997)

units		lj
atom_style	dpd
pair_style	dpd 1.0 1.0 34387

# create simulation box
lattice		fcc 3
region		mybox block -4 4 -4 4 -4 4 units lattice
create_box	1 mybox
create_atoms	1 box

# define masses and interaction coefficient
mass		* 1
pair_coeff	1 1 25 4.5

# create initial velocities
velocity	all create 1.0 4928459 dist gaussian 

# change neighbor list parameters to avoid dangerous builds
neighbor	2.0 bin
neigh_modify	delay 3

# specify simulation parameters
timestep	0.04
thermo		10

# first equilibrate the initial condition
fix		1 all nve
run		500

# production run
fix		2 all rdf 20 dpd_example.rdf 100 1 1
run		500