75 lines
1.8 KiB
ReStructuredText
75 lines
1.8 KiB
ReStructuredText
.. index:: compute contact/atom
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compute contact/atom command
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============================
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Syntax
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""""""
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.. parsed-literal::
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compute ID group-ID contact/atom group2-ID
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* ID, group-ID are documented in :doc:`compute <compute>` command
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* contact/atom = style name of this compute command
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* group2-ID = optional argument to restrict which atoms to consider for contacts (see below)
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Examples
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""""""""
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.. code-block:: LAMMPS
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compute 1 all contact/atom
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compute 1 all contact/atom mygroup
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Description
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"""""""""""
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Define a computation that calculates the number of contacts
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for each atom in a group.
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The contact number is defined for finite-size spherical particles as
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the number of neighbor atoms which overlap the central particle,
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meaning that their distance of separation is less than or equal to the
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sum of the radii of the two particles.
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The value of the contact number will be 0.0 for atoms not in the
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specified compute group.
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Output info
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"""""""""""
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This compute calculates a per-atom vector, whose values can be
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accessed by any command that uses per-atom values from a compute as
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input. See the :doc:`Howto output <Howto_output>` page for an
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overview of LAMMPS output options.
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The per-atom vector values will be a number >= 0.0, as explained
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above.
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The optional *group2-ID* argument allows to specify from which group atoms
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contribute to the coordination number. Default setting is group 'all'.
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Restrictions
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""""""""""""
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This compute is part of the GRANULAR package. It is only enabled if
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LAMMPS was built with that package. See the
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:doc:`Build package <Build_package>` page for more info.
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This compute requires that atoms store a radius as defined by the
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:doc:`atom_style sphere <atom_style>` command.
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Related commands
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""""""""""""""""
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:doc:`compute coord/atom <compute_coord_atom>`
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Default
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"""""""
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*group2-ID* = all
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none
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