forked from lijiext/lammps
96 lines
3.5 KiB
Plaintext
96 lines
3.5 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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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 \
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{dpd} or {ellipsoid} or {full} or {granular} or {molecular} or \
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{hybrid} :ul
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args = none for any style except {hybrid}
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{hybrid} args = list of one or more sub-styles :pre
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[Examples:]
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atom_style atomic
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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 and dipole moment
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{dpd} = default values, also communicates velocities
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{ellipsoid} = quaternion for particle orientation, angular velocity/momentum
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{full} = molecular + charge - e.g. biomolecules, charged polymers
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{granular} = granular atoms with rotational properties
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{molecular} = bonds, angles, dihedrals, impropers - e.g. all-atom polymers :ul
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Typically, simulations require only a single (non-hybrid) atom style.
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If some atoms in the simulation do not have all the properties defined
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by a particular style, use the simplest style that defines all the
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needed properties by any atom. For example, if some atoms in a
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simulation are charged, but others are not, use the {charge} style.
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If some atoms have bonds, but others do not, use the {bond} style.
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The only scenario where the {hybrid} style is needed is if there is no
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single style which defines all needed properties of all atoms.
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E.g. if you want charged DPD particles, you would need to use
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"atom_style hybrid dpd charge". When a hybrid style is used, atoms
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store and communicate the union of all quantities implied by the
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individual 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. The {dipole}
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style is part of the "dipole" package. The {ellipsoid} style is part
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of the "ellipsoid" package. They are only enabled if LAMMPS was built
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with that package. See the "Making LAMMPS"_Section_start.html#2_3
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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:]
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atom_style atomic
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