Added example script and input data file showing benefits of new fix gravity and fix rigid options

#Pour composite granular particles on flat wall

newton		on

atom_style	sphere

atom_modify	map array sort 0 0

thermo_modify	flush yes

units 		si  

variable	minrad equal 0.5

variable	maxrad equal 1.4

variable 	skin equal 0.3*${maxrad}

boundary	p p f

region		reg block 0 20 0 20 0 200 units box

create_box	1 reg

fix             prop all property/atom mol ghost yes

variable	dumpfreq equal 1000

variable	logfreq equal 1000

pair_style	gran/hooke/history 4e5 NULL 1e2 NULL 0.5 0

pair_coeff	* *

timestep 	0.0001

group		particles type 1

atom_modify     first particles

neighbor        ${skin} bin

group		rigid type 1

neigh_modify	every 1 delay 0 check yes exclude molecule/intra all 

thermo 		${logfreq}

thermo_style	custom step cpu atoms ke

thermo_modify	flush yes lost warn

comm_modify	vel yes cutoff 3

molecule	mymol molecule.data

region		pourreg block 5 15 5 15 80 100 side in units box

#Note: in versions prior to 1/2020, the 'disable' keyword to fix/gravity

# and the 'gravity' keyword to fix rigid/small were not available.

# These settings produce undesirable behavior, where gravity can induce

# torque on rigid bodies.

#fix		gravfix all gravity 9.8 vector 0 0 -1 #disable

#fix		rigidfix all rigid/small molecule mol mymol #gravity gravfix

#The correct behavior is recovered with the following settings:

fix		gravfix all gravity 9.8 vector 0 0 -1 disable

fix		rigidfix all rigid/small molecule mol mymol gravity gravfix

fix		pourfix all pour 5 0 1234 region pourreg mol mymol rigid rigidfix

fix		zwall all wall/gran hooke/history 4000.0 NULL 100.0 NULL 0.5 0 zplane 0.1 NULL

dump		1 all custom 1000 molecule_pour.dump id type mass radius x y z fx fy fz

run		100000

LAMMPS data file created for rigid body molecule template

5 atoms

2.3388800000000005 mass

6.002239704473936 4.99 4.989999999999999 com

116.79265620480001 144.26721336320003 144.26721336320006 -70.05220681600004 -70.05220681600002 -58.238345888000005 inertia

Coords

1 5 5 5

2 5.1 5.0 5.0

3 5.2 5.0 5.0

4 6.2 5.0 5.0

5 7.2 5.0 5.0

Types

1 1

2 1

3 1

4 1

5 1

Diameters

1 1.0

2 0.9

3 1.2

4 1.2

5 1.0

Masses

1 0.5235987755982988

2 0.3817035074111599

3 0.9047786842338602

4 0.9047786842338602

5 0.5235987755982988