forked from lijiext/lammps
90 lines
3.3 KiB
Plaintext
90 lines
3.3 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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compute body/local command :h3
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[Syntax:]
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compute ID group-ID body/local input1 input2 ... :pre
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ID, group-ID are documented in "compute"_compute.html command :ulb,l
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body/local = style name of this compute command :l
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one or more keywords may be appended :l
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keyword = {type} or {integer} :l
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{type} = atom type of the body particle
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{integer} = 1,2,3,etc = index of fields defined by body style :pre
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:ule
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[Examples:]
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compute 1 all body/local type 1 2 3
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compute 1 all body/local 3 6 :pre
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[Description:]
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Define a computation that calculates properties of individual body
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sub-particles. The number of datums generated, aggregated across all
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processors, equals the number of body sub-particles plus the number of
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non-body particles in the system, modified by the group parameter as
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explained below. See "Section_howto 14"_Section_howto.html#howto_14
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of the manual and the "body"_body.html doc page for more details on
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using body particles.
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The local data stored by this command is generated by looping over all
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the atoms. An atom will only be included if it is in the group. If
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the atom is a body particle, then its N sub-particles will be looped
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over, and it will contribute N datums to the count of datums. If it
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is not a body particle, it will contribute 1 datum.
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For both body particles and non-body particles, the {type} keyword
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will store the type of the atom.
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The {integer} keywords mean different things for body and non-body
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particles. If the atom is not a body particle, only its {x}, {y}, {z}
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coordinates can be referenced, using the {integer} keywords 1,2,3.
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Note that this means that if you want to access more fields than this
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for body particles, then you cannot include non-body particles in the
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group.
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For a body particle, the {integer} keywords refer to fields calculated
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by the body style for each sub-particle. The body style, as specified
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by the "atom_style body"_atom_style.html, determines how many fields
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exist and what they are. See the "body"_body.html doc page for
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details of the different styles.
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Here is an example of how to output body information using the "dump
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local"_dump.html command with this compute. If fields 1,2,3 for the
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body sub-particles are x,y,z coordinates, then the dump file will be
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formatted similar to the output of a "dump atom or custom"_dump.html
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command.
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compute 1 all body/local type 1 2 3
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dump 1 all local 1000 tmp.dump index c_1\[1\] c_1\[2\] c_1\[3\] c_1\[4\] :pre
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[Output info:]
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This compute calculates a local vector or local array depending on the
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number of keywords. The length of the vector or number of rows in the
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array is the number of datums as described above. If a single keyword
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is specified, a local vector is produced. If two or more keywords are
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specified, a local array is produced where the number of columns = the
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number of keywords. The vector or array can be accessed by any
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command that uses local values from a compute as input. See "this
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section"_Section_howto.html#howto_15 for an overview of LAMMPS output
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options.
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The "units"_units.html for output values depend on the body style.
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[Restrictions:] none
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[Related commands:]
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"dump local"_dump.html
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[Default:] none
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