LAMMPS (7 Jul 2009)
# 2d friction simulation

dimension	2
boundary	p s p

atom_style	atomic
neighbor	0.3 bin
neigh_modify	delay 5

# create geometry

lattice		hex 0.9
Lattice spacing in x,y,z = 1.1327 1.96189 1.1327
region		box block 0 50 0 22 -0.25 0.25
create_box	4 box
Created orthogonal box = (0 0 -0.283174) to (56.6348 43.1615 0.283174)
  1 by 1 by 1 processor grid

mass		1 1.0
mass		2 1.0
mass		3 1.0
mass		4 1.0

# atom regions

region          lo-fixed block INF INF INF 1.1 INF INF
region          lo-slab block INF INF INF 7 INF INF
region          above-lo block INF INF INF 7 INF INF side out
region          hi-fixed block INF INF 20.9 INF INF INF
region          hi-slab block INF INF 15 INF INF INF
region          below-hi block INF INF 15 INF INF INF side out
region		lo-asperity sphere 32 7 0 8
region		hi-asperity sphere 18 15 0 8
region		lo-half-sphere intersect 2 lo-asperity above-lo
region		hi-half-sphere intersect 2 hi-asperity below-hi

# create 2 surfaces with asperities

create_atoms	1 region lo-slab
Created 750 atoms
create_atoms	1 region hi-slab
Created 750 atoms
create_atoms	2 region lo-half-sphere
Created 112 atoms
create_atoms	3 region hi-half-sphere
Created 112 atoms

# LJ potentials

pair_style	lj/cut 2.5
pair_coeff	* * 1.0 1.0 2.5

# define groups

group	        lo region lo-slab
750 atoms in group lo
group		lo type 2
862 atoms in group lo
group		hi region hi-slab
750 atoms in group hi
group		hi type 3
862 atoms in group hi
group		lo-fixed region lo-fixed
150 atoms in group lo-fixed
group		hi-fixed region hi-fixed
150 atoms in group hi-fixed
group		boundary union lo-fixed hi-fixed
300 atoms in group boundary
group		mobile subtract all boundary
1424 atoms in group mobile

set		group lo-fixed type 4
  150 settings made for type
set		group hi-fixed type 4
  150 settings made for type

# initial velocities

compute         new mobile temp/partial 0 1 0
velocity	mobile create 0.1 482748 temp new
velocity	hi set 1.0 0.0 0.0 sum yes

# fixes

fix		1 all nve
fix		2 boundary setforce 0.0 0.0 0.0
fix		3 mobile temp/rescale 200 0.1 0.1 0.02 1.0
fix_modify	3 temp new

# Run

timestep	0.0025
thermo		1000
thermo_modify	temp new

dump		1 all atom 500 dump.friction
run		20000
Memory usage per processor = 1.73539 Mbytes
Step Temp E_pair E_mol TotEng Press Volume 
       0          0.1   -3.1333672            0   -3.0921259   -1.1440102    2444.4558 
    1000          0.1   -3.0915465            0   -3.0503052  0.010017516    2444.4558 
    2000          0.1   -3.0826487            0   -3.0414074  -0.42021097    2444.4558 
    3000  0.089819692     -3.07584            0   -3.0387972  -0.25257042    2444.4558 
    4000  0.098489874   -3.0667093            0   -3.0260907  -0.25511521    2444.4558 
    5000   0.11379986   -3.0557087            0   -3.0087762 -0.080886978    2444.4558 
    6000   0.11269179     -3.04532            0   -2.9988445  -0.33387724    2444.4558 
    7000          0.1   -3.0380598            0   -2.9968185  -0.32430283    2444.4558 
    8000          0.1   -3.0346457            0   -2.9934044  -0.38023276    2444.4558 
    9000          0.1   -3.0327792            0   -2.9915379  -0.43204961    2444.4558 
   10000   0.11908329   -3.0384756            0   -2.9893641  -0.34377218    2444.4558 
   11000          0.1   -3.0307666            0   -2.9895253  -0.46039249    2444.4558 
   12000   0.11748666   -3.0410033            0   -2.9925503  -0.21956005    2444.4558 
   13000          0.1   -3.0416003            0    -3.000359   -0.3651589    2444.4558 
   14000   0.11069381   -3.0439855            0    -2.998334  -0.28704457    2444.4558 
   15000   0.11218605   -3.0480708            0   -3.0018038  -0.32666261    2444.4558 
   16000   0.11189162   -3.0483127            0   -3.0021671  -0.23171462    2444.4558 
   17000   0.11423906   -3.0474938            0   -3.0003802  -0.34260897    2444.4558 
   18000   0.11548632    -3.047828            0      -3.0002  -0.31060102    2444.4558 
   19000   0.10034246   -3.0488263            0   -3.0074438   -0.2527683    2444.4558 
   20000   0.10505024   -3.0494404            0   -3.0061164  -0.31791192    2444.4558 
Loop time of 10.8242 on 1 procs for 20000 steps with 1724 atoms

Pair  time (%) = 9.04606 (83.5728)
Neigh time (%) = 0.446001 (4.12042)
Comm  time (%) = 0.0695286 (0.642346)
Outpt time (%) = 0.105748 (0.976966)
Other time (%) = 1.15683 (10.6875)

Nlocal:    1724 ave 1724 max 1724 min
Histogram: 1 0 0 0 0 0 0 0 0 0
Nghost:    146 ave 146 max 146 min
Histogram: 1 0 0 0 0 0 0 0 0 0
Neighs:    14389 ave 14389 max 14389 min
Histogram: 1 0 0 0 0 0 0 0 0 0

Total # of neighbors = 14389
Ave neighs/atom = 8.34629
Neighbor list builds = 723
Dangerous builds = 0
