LIGGGHTS 2.2.4: (released 24 January 2013)
+ Added an 'sjkr2' cohesion model for pair gran and fix wall/gran. It calculates the sphere-sphere contact area differently, i.e. A = 2*Pi * normal_overlap * (2 R), where R = ri*rj/(ri+rj).
+ Added a 'force off' keyword to pair gran to turn off all force computation of granular pair styles. This can be useful if you want to use pair granular in the frame of a hybrid pair style and just want to turn off the granular part.
+ Added a feature into pair gran to vary the coefficient of restitution depending on the local Stokes number. Thanks to Joris Heyman (EPFL) for this contribution.
+ Fixed a bug that could lead to a hang instead of an error message when the insertion region was too small to insert particles. Thanks to Andrew Hobbs (Astec Inc) for sending an example case
+ Fixed an issue with fix move/mesh superposition. Thanks to Christian Richter (OVGU Magdeburg) for sending a test case.
+ Fixed an issue with constistency of shear history across multiple runs or restart if compute pair/gran/local or compute/wall/gran/local was used.
+ Fixed an issue where in some rare cases there was not enough memory allocated for shear history when restarting a simulation.
+ Fixed an issue where the wall velocity used for the damping term for particle-wall collisions was slightly off in some rare cases.
+ Fixed an issue where particles were not inserted correctly when two fix insert/stream commands were used at the same time. Thanks to Chris Stoltz (PG) for sending a test case.
However, there are some restrictions in 2.2.4 (see below) which will be relaxed over time:
+ fix breakparticle/force is not yet available
BACKWARD COMPATIBILITY: You may not be able to use restart files with 2.2.4 that were generated by older version of LIGGGHTS