forked from lijiext/lammps
85 lines
3.0 KiB
Plaintext
85 lines
3.0 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 bond/local command :h3
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[Syntax:]
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compute ID group-ID bond/local input1 input2 ... :pre
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ID, group-ID are documented in "compute"_compute.html command :ulb,l
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bond/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 = {dist} or {eng} :l
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{dist} = bond distance
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{eng} = bond energy
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{force} = bond force :pre
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:ule
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[Examples:]
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compute 1 all bond/local eng
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compute 1 all bond/local dist eng force :pre
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[Description:]
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Define a computation that calculates properties of individual bond
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interactions. The number of datums generated, aggregated across all
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processors, equals the number of bonds in the system, modified
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by the group parameter as explained below.
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The local data stored by this command is generated by looping over all
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the atoms owned on a processor and their bonds. A bond will only be
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included if both atoms in the bond are in the specified compute group.
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Any bonds that have been broken (see the "bond_style"_bond_style.html
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command) by setting their bond type to 0 are not included. Bonds that
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have been turned off (see the "fix shake"_fix_shake.html or
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"delete_bonds"_delete_bonds.html commands) by setting their bond type
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negative are written into the file, but their energy will be 0.0.
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Note that as atoms migrate from processor to processor, there will be
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no consistent ordering of the entries within the local vector or array
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from one timestep to the next. The only consistency that is
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guaranteed is that the ordering on a particular timestep will be the
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same for local vectors or arrays generated by other compute commands.
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For example, bond output from the "compute
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property/local"_compute_property_local.html command can be combined
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with data from this command and output by the "dump local"_dump.html
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command in a consistent way.
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Here is an example of how to do this:
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compute 1 all property/local batom1 batom2 btype
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compute 2 all bond/local dist eng
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dump 1 all local 1000 tmp.dump index c_1\[1\] c_1\[2\] c_1\[3\] c_2\[1\] c_2\[2\] :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 bonds. If a single keyword is specified, a
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local vector is produced. If two or more keywords are specified, a
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local array is produced where the number of columns = the number of
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keywords. The vector or array can be accessed by any command that
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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 output for {dist} will be in distance "units"_units.html. The
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output for {eng} will be in energy "units"_units.html. The output for
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{force} will be in force "units"_units.html.
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[Restrictions:] none
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[Related commands:]
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"dump local"_dump.html, "compute
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property/local"_compute_property_local.html
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[Default:] none
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