### DPD binary mixture

dimension    3
units        lj
comm_modify  vel yes
newton       off

atom_style   atomic
neighbor     0.3 bin
neigh_modify delay 0 every 4 check no

region       domain block -5 5 -5 5 -5 5 units box
create_box   2 domain
lattice      fcc 4
create_atoms 1 random 1500 15255 domain
create_atoms 2 random 1500 47214 domain
mass         * 1.0

pair_style   dpd 1.0 1.0 419084618
pair_coeff   1 1 25.0 4.5
pair_coeff   1 2 150.0 4.5
pair_coeff   2 2 25.0 4.5

thermo       100
dump         dump0 all atom 5 bin.lammpstrj

velocity     all create 1.0 8178251
fix          integrator all nve

timestep     0.01
run          10000 

# Compute the diffusion coefficient

variable        dt equal 0.01


fix            1 all nvt temp 1.0 1.0 0.01  

compute         msd all msd com yes
variable        D equal c_msd[4]/6/(step*${dt}+1.0e-6)  
fix             9 all vector 10 c_msd[4]
variable        fitslope equal slope(f_9)/6/(10*${dt}) 
variable        Time equal step*${dt}*1.0e-6
thermo_style	custom step v_Time temp press c_msd[4] v_D v_fitslope 

thermo          1000
run             100000