lammps/examples/srd/in.srd.mixture

# 2d SRD test: big + small particles

units		lj
atom_style	sphere
atom_modify	first big
dimension	2

# create big particles with sigma 1.0

lattice		sq 0.4
region		box block 0 10 0 10 -0.5 0.5
create_box	2 box
create_atoms	1 region box
set		type 1 mass 1.0
set		type 1 diameter 1.0

group		big type 1
velocity	big create 1.44 87287 loop geom

# equilibrate big particles

pair_style	lj/cut 2.5
pair_coeff	1 1 1.0 1.0
pair_coeff	2 2 0.0 1.0 0.0
pair_coeff	1 2 0.0 1.0 0.0

neighbor	0.3 bin
neigh_modify	delay 0 every 1 check yes

fix		1 big nve
fix		2 all enforce2d

run		1000

unfix		1
unfix		2

# add small particles as hi density lattice

lattice		sq 0.4
region		plane block 0 10 0 10 -0.001 0.001
lattice		sq 85.0
create_atoms	2 region plane
set		type 2 mass 0.01
set		type 2 diameter 0.0

group		small type 2

velocity	small create 1.0 593849 loop geom

# delete overlaps
# must set 1-2 cutoff to non-zero value

pair_style	lj/cut 2.5
pair_coeff	1 1 1.0 1.0
pair_coeff	2 2 0.0 1.0 0.0
pair_coeff	1 2 0.0 1.0 0.5

delete_atoms	overlap 0.5 small big

# SRD run

reset_timestep	0

neighbor	0.3 bin
neigh_modify	delay 0 every 1 check yes

communicate	multi group big vel yes
neigh_modify	include big

# no pairwise interactions with small particles

pair_style	lj/cut 2.5
pair_coeff	1 1 1.0 1.0
pair_coeff	2 2 0.0 1.0 0.0
pair_coeff	1 2 0.0 1.0 0.0

# use fix SRD to push small particles out from inside big ones

timestep	0.001

fix		1 big nve
fix	        2 small srd 20 big 1.0 0.25 49894 &
		  radius 0.88 search 0.2 collision slip
fix		3 all enforce2d

# diagnostics

compute		tbig big temp
variable	pebig equal pe*atoms/count(big)
variable	ebig equal etotal*atoms/count(big)
thermo_style	custom step temp f_2[7] etotal v_pebig v_ebig press &
		f_2[1] f_2[2] f_2[3] f_2[4] f_2[5] &
		f_2[6] f_2[8] f_2[9] f_2[10]

thermo_modify	temp tbig
thermo		100
dump		1 all atom 250 dump.srd.mixture

run		5000