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compute bond/gran/disk/local command

Syntax:

compute ID group-ID bond/gran/disk/local keyword1 keyword2 ... 

Examples:

compute 1 all bond/gran/disk/local thickness
compute 1 all bond/gran/disk/local length forcen forcet torquetz 

Description:

This command is part of the USER-SEAICE package; it is only enabled if LIGGGHTS was built with that package.

It defines a computation that calculates properties of individual bond interactions for granular bonds and disk-shaped atoms (atom_style hybrid disk bond/gran/disk or atom_style hybrid disk disk/waves bond/gran/disk and bond_style gran/disk or bond_style gran/disk/waves). The number of datums generated, aggregated across all processors, equals the number of bonds in the system, modified by the group parameter as explained below.

The keywords torquen and torqueth are allowed only in computations with waves, as they describe moments due to twisting of the bonds and their bending out of the horizontal xy-plane.

The local data stored by this command is generated by looping over all the atoms owned on a processor and their bonds. A bond will only be included if both atoms in the bond are in the specified compute group. Any bonds that have been broken are not included.

Note that as atoms migrate from processor to processor, there will be no consistent ordering of the entries within the local vector or array from one timestep to the next. The only consistency that is guaranteed is that the ordering on a particular timestep will be the same for local vectors or arrays generated by other compute commands. For example, bond output from the compute property/local command can be combined with data from this command and output by the dump local command in a consistent way. Here is an example of how to do this:

compute 1 all property/local batom1 batom2 btype 
compute 2 all bond/gran/disk/local forcen forcet
dump 1 all local 1000 tmp.dump index c_1[1] c_1[2] c_1[3] c_2[1] c_2[2] 

Output info:

See the documentation of the compute bond/local for details.

The amplitude of the forces and torques is calculated differently for purely two-dimensional simulations and for quasi-three-dimensional simulations.

Restrictions: none

Related commands:

compute bond/local, dump local, compute property/local

Default: none

(Herman) Agnieszka Herman, Geosci. Model Devel., submitted (2015).