LAMMPS (15 Jan 2010)
# 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  -0.32430244    2444.4558 
    8000          0.1   -3.0346458            0   -2.9934045  -0.38022997    2444.4558 
    9000          0.1   -3.0323928            0   -2.9911515  -0.42944097    2444.4558 
   10000          0.1   -3.0354969            0   -2.9942556   -0.3547036    2444.4558 
   11000   0.11248007   -3.0371526            0   -2.9907643  -0.42222237    2444.4558 
   12000   0.10241295   -3.0422315            0   -2.9999951  -0.24193736    2444.4558 
   13000   0.11139984    -3.044969            0   -2.9990263  -0.32692165    2444.4558 
   14000  0.099297055   -3.0415792            0   -3.0006278  -0.34441013    2444.4558 
   15000   0.11494243    -3.045278            0   -2.9978742  -0.26868839    2444.4558 
   16000   0.11211716   -3.0460201            0   -2.9997815  -0.27620024    2444.4558 
   17000   0.11246574   -3.0461857            0   -2.9998034  -0.31782055    2444.4558 
   18000   0.11194476   -3.0440786            0   -2.9979112  -0.35902467    2444.4558 
   19000   0.11200621   -3.0473992            0   -3.0012064  -0.25540459    2444.4558 
   20000   0.10818968   -3.0456459            0   -3.0010271  -0.29452342    2444.4558 
Loop time of 10.662 on 1 procs for 20000 steps with 1724 atoms

Pair  time (%) = 8.89733 (83.4491)
Neigh time (%) = 0.434347 (4.07379)
Comm  time (%) = 0.0713072 (0.668798)
Outpt time (%) = 0.105844 (0.992721)
Other time (%) = 1.15316 (10.8156)

Nlocal:    1724 ave 1724 max 1724 min
Histogram: 1 0 0 0 0 0 0 0 0 0
Nghost:    145 ave 145 max 145 min
Histogram: 1 0 0 0 0 0 0 0 0 0
Neighs:    14369 ave 14369 max 14369 min
Histogram: 1 0 0 0 0 0 0 0 0 0

Total # of neighbors = 14369
Ave neighs/atom = 8.33469
Neighbor list builds = 717
Dangerous builds = 0
