units		lj
dimension	2
boundary        p p p
atom_style	  sphere 
                                                                             
region		box block 0 42 0 42 -0.01 0.01
create_box	2 box
region		mybox block 0 42 0 42 -0.01 0.01 units box
lattice		sq 0.41 origin 0.3 0.4  0.0
create_atoms	1 region mybox
group		substrate type 1
set		group substrate diameter  1.0
set		group substrate mass  1.0

region		mbox block 0 42 0 42 -0.01 0.01 units box
lattice		sq 0.41 origin 0.4 0.4  0.0
create_atoms	2 region mbox
group		mobile type 1
set		group mobile diameter 1.0
set		group mobile mass  1.0

pair_style	lj/cut 2.5
pair_coeff	1 1 1.0 1.0 1.122
pair_coeff	2 2 1.0 1.0 1.112
pair_coeff	1 2 0.7 0.16 2.5
pair_modify shift yes 
neighbor	0.2 bin
neigh_modify	delay 1 every 1 check yes
fix		    1 mobile nve/sphere 
fix             4 mobile langevin 1.0 1.0 10.0 437624 omega yes scale 1 3.3  
fix             fric mobile viscous 1.0
fix		 2 all enforce2d
timestep	0.0002
run		1000
unfix 4

# run in loop...........................................................
label loop0
variable a loop 4
variable f index 0.897,0.898,0.899,0.890
log log.$a
fix             active1 mobile propel/self velocity 0.015
fix             3 mobile addforce $f 0.0 0.0

compute  xvel mobile property/atom vx
compute sumvx mobile reduce sum c_xvel
compute yvel mobile property/atom vy
compute sumvy mobile reduce sum c_yvel
                                                     
dump		1 all atom 50 dump.$a
dump DUMP all custom 50 dump.lammpstrj id type x y z 
vthermo_style custom step c_sumvx c_sumvy 
thermo 1000
timestep	0.0002           
run		1000
clear
next f
next a
jump in.code1 loop0