forked from lijiext/lammps
69 lines
2.4 KiB
Plaintext
69 lines
2.4 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 group/group command :h3
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[Syntax:]
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compute ID group-ID group/group group2-ID :pre
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ID, group-ID are documented in "compute"_compute.html command
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group/group = style name of this compute command
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group2-ID = group ID of second (or same) group :ul
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[Examples:]
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compute 1 lower group/group upper
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compute mine fluid group/group wall :pre
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[Description:]
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Define a computation that calculates the total energy and force
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interaction between two groups of atoms: the compute group and the
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specified group2. The two groups can be the same. The interaction
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energy is defined as the pairwise energy between all pairs of atoms
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where one atom in the pair is in the first group and the other is in
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the second group. Likewise, the interaction force calculated by this
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compute is the force on the compute group atoms due to pairwise
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interactions with atoms in the specified group2.
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The energy and force are calculated by looping over a neighbor list of
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pairwise interactions. Thus it can be inefficient to compute this
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quantity too frequently.
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[Output info:]
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This compute calculates a global scalar (the energy) and a global
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vector of length 3 (force), which can be accessed by indices 1-3.
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These values can be used by any command that uses global scalar or
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vector 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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Both the scalar and vector values calculated by this compute are
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"extensive". The scalar value will be in energy "units"_units.html.
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The vector values will be in force "units"_units.html.
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[Restrictions:]
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Only pairwise interactions, as defined by the
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"pair_style"_pair_style.html command, are included in this
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calculation. Bond (angle, dihedral, etc) interactions between atoms
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in the two groups are not included. Long-range interactions due to a
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"kspace_style"_kspace_style.html command are also not included. Not
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all pair potentials can be evaluated in a pairwise mode as required by
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this compute. For example, 3-body potentials, such as
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"Tersoff"_pair_tersoff.html and "Stillinger-Weber"_pair_sw.html cannot
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be used. "EAM"_pair_eam.html potentials for metals only include the
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pair potential portion of the EAM interaction, not the embedding
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term.
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[Related commands:] none
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[Default:] none
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