forked from lijiext/lammps
85 lines
3.0 KiB
Plaintext
85 lines
3.0 KiB
Plaintext
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"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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atom_style command :h3
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[Syntax:]
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atom_style style args :pre
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style = {angle} or {atomic} or {bond} or {charge} or {dipole} or {dpd} or \
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{full} or {granular} or {molecular} or {hybrid} :ul
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args = none for any style except {hybrid}
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{hybrid} args = list of one or more styles :pre
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[Examples:]
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atom_style bond
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atom_style full
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atom_style hybrid charge bond :pre
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[Description:]
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Define what style of atoms to use in a simulation. This determines
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what attributes are associated with the atoms. This command must be
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used before a simulation is setup via a "read_data"_read_data.html,
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"read_restart"_read_restart.html, or "create_box"_create_box.html
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command.
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Once a style is assigned, it cannot be changed, so use a style general
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enough to encompass all attributes. E.g. with style {bond}, angular
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terms cannot be used or added later to the model. It is OK to use a
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style more general than needed, though it may be slightly inefficient.
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The choice of style affects what quantities are stored by each atom,
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what quantities are communicated between processors to enable forces
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to be computed, and what quantities are listed in the data file read
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by the "read_data"_read_data.html command.
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These are the attributes of each style. All styles store coordinates,
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velocities, atom IDs and types.
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{angle} = bonds and angles - e.g. bead-spring polymers with stiffness
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{atomic} = only the default values
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{bond} = bonds - e.g. bead-spring polymers
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{charge} = charge
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{dipole} = charge + dipole moments
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{dpd} = default values, also communicates velocities
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{molecular} = bonds, angles, dihedrals, impropers - e.g. all-atom polymers
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{full} = molecular + charge - e.g. biomolecules, charged polymers
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{granular} = granular material with rotational properties :ul
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Typical simulations with a single pair potential will use only one of
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these styles. For cases where multiple pair potentials will be used
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(see the "pair_style"_pair_style.html {hybrid} command), it may be
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necessary to use multiple atom styles. Another example is doing a DPD
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simulations with bonds or angles. In these cases the {hybrid} style
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can be used to list multiple atom styles. Atoms will then store and
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communicate the union of all quantities implied by the individual
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styles.
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LAMMPS can be extended with new atom styles; see "this
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section"_Section_modify.html.
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[Restrictions:]
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This command cannot be used after the simulation box is defined by a
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"read_data"_read_data.html or "create_box"_create_box.html command.
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The {angle}, {bond}, {full}, and {molecular} styles are part of the
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"molecular" package. The {granular} style is part of the "granular"
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package. The {dpd} style is part of the "dpd" package. They are only
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enabled if LAMMPS was built with that package. See the "Making
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LAMMPS"_Section_start.html#2_2 section for more info.
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[Related commands:]
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"read_data"_read_data.html, "pair_style"_pair_style.html
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[Default:] none
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