Merge pull request #1838 from lammps/stochastic-example

threebody: regression test input for a variety of manybody potentials

vashishta: models using the Vashishta potential

voronoi:  Voronoi tesselation via compute voronoi/atom command

wall:     use of reflective walls with different stochastic models

Here is how you might run and visualize one of the sample problems:

units		metal

dimension	3

boundary	p f p

atom_style		atomic

neighbor		2.0 bin

# create geometry

lattice		sc 10

region			box block 0 10 0 10 0 10

create_box		1 box

create_atoms	1 box

mass		1 39.95

# LJ potentials

pair_style	lj/cut 8.5

pair_coeff	* * 0.01 3.4 8.5

# initial velocities

velocity	all create 300 482748 

fix			1 all nve

# Mirror reflection

#fix ywalls all wall/reflect ylo EDGE yhi EDGE

# Diffusive reflection, upper wall velocity = 0.1, lower wall fixed

#fix ywalls all wall/stochastic diffusive 2308 ylo EDGE 300 0 0 0 yhi EDGE 300 0.1 0 0

# Maxwell wall, upper wall velocity = 0.1, lower wall fixed, accommodation coefficient = 0.2 for both walls

#fix ywalls all wall/stochastic maxwell ylo EDGE 300 0 0 0 0.2 yhi EDGE 300 0 0 0.1 0.2 

# Diffusive reflection, upper wall velocity = 0.1, lower wall fixed, accommodation coefficients = 0.1, 0.2 and 0.3 along directions x,y,z

fix ywalls all wall/reflect/stochastic 345533 cercignanilampis ylo EDGE 300 0 0 0 0.1 0.2 0.3 yhi EDGE 300 0.1 0 0 0.1 0.2 0.3

# Run

thermo			1000

run		1000000

units		metal

dimension	3

boundary	p f p

atom_style	atomic

neighbor	2.0 bin

# create geometry

lattice		sc 10

region		box block 0 10 0 10 0 10

create_box	1 box

create_atoms	1 box

mass		1 39.95

# LJ potentials

pair_style	lj/cut 8.5

pair_coeff	* * 0.01 3.4 8.5

# initial velocities

velocity	all create 300 482748 

fix		1 all nve

# CCL reflection model

# upper wall velocity = 0.1, lower wall fixed,

# accommodation coefficients = 0.1, 0.2 and 0.3 along directions x,y,z

fix ywalls all wall/reflect/stochastic ccl 345533 &

    ylo EDGE 300 0 0 0 0.1 0.2 0.3 yhi EDGE 300 0.1 0 0 0.1 0.2 0.3

# run

thermo		1000

run		10000

units		metal

dimension	3

boundary	p f p

atom_style	atomic

neighbor	2.0 bin

# create geometry

lattice		sc 10

region		box block 0 10 0 10 0 10

create_box	1 box

create_atoms	1 box

mass		1 39.95

# LJ potentials

pair_style	lj/cut 8.5

pair_coeff	* * 0.01 3.4 8.5

# initial velocities

velocity	all create 300 482748 

fix		1 all nve

# diffusive reflection

# upper wall velocity = 0.1, lower wall fixed

fix ywalls all wall/reflect/stochastic diffusive 2308 &

     ylo EDGE 300 0 0 0 yhi EDGE 300 0.1 0 0

# run

thermo		1000

run		10000

units		metal

dimension	3

boundary	p f p

atom_style	atomic

neighbor	2.0 bin

# create geometry

lattice		sc 10

region		box block 0 10 0 10 0 10

create_box	1 box

create_atoms	1 box

mass		1 39.95

# LJ potentials

pair_style	lj/cut 8.5

pair_coeff	* * 0.01 3.4 8.5

# initial velocities

velocity	all create 300 482748 

fix		1 all nve

# Maxwellian reflection

# upper wall velocity = 0.1, lower wall fixed, 

# accommodation coefficient = 0.2 for both walls

fix ywalls all wall/reflect/stochastic maxwell 29839 &

     ylo EDGE 300 0 0 0 0.2 yhi EDGE 300 0 0 0.1 0.2 

# run

thermo		1000

run		10000