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:link(ld,Manual.html)
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gran cohesion sjkr2 :h3

[Syntax:]

cohesion sjkr2 :pre

[LIGGGHTS vs. LAMMPS Info:]

This part of "pair gran"_pair_gran.html and 
"fix wall/gran"_fix_wall_gran.html
is not availabe in LAMMPS.

[Description:]

This model can be used as part of "pair gran"_pair_gran.html and 
"fix wall/gran"_fix_wall_gran.html

The modified simplified JKR - Johnson-Kendall-Roberts (SJKR2) model adds an additional normal force
contribution. If two particle are in contact, it adds an additional normal force tending 
to maintain the contact, which writes 

F = k A, 

where A is the particle contact area and k is the cohesion energy density in J/m3. 
For {sjkr2}, the sphere-sphere contact area is calculated as

A = 2*Pi * delta_n * (2R*)

If you are using the SJKR2 model, you must also define the cohesion energy density:

fix id all property/global cohesionEnergyDensity peratomtypepair n_atomtypes value_11 value_12 .. value_21 value_22 .. .
    (value_ij=value for the cohesion energy density (in Energy/Length3 units) between atom type i and j; n_atomtypes is the number of atom types you want to use in your simulation) :pre

IMPORTANT NOTE: The cohesion model has been derived for the Hertzian Style, it may note be 
appropriate for the Hookean styles.

IMPORTANT NOTE: You have to use atom styles beginning from 1, e.g. 1,2,3,...

[Restrictions:]

The cohesion model has been derived for the Hertzian Style, it may note be 
appropriate for the Hookean styles.
