forked from lijiext/lammps
102 lines
3.7 KiB
Plaintext
102 lines
3.7 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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set command :h3
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[Syntax:]
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set ID style value :pre
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ID = ID of group or atom
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style = {atom} or {bond} or {angle} or {dihedral} or {improper} or \
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{charge} or {dipole} or {type} or {mol} or {x} or {y} or {z} or \
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{vx} or {vy} or {vz} or {q}
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value = value to set selected atom(s) to :ul
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[Examples:]
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set solvent atom 2
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set edge bond 4
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set half charge 0.5
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set 100 x 0.5
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set 1492 type 3 :pre
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[Description:]
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Set an attribute for a single atom or each atom in a group. The
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context depends on the specified {style}.
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Styles {atom}, {bond}, {angle}, {dihedral}, {improper}, {charge}, and
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{dipole} set attributes for all atoms in a group, so the specified ID
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is a group-ID string.
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Styles {type}, {mol}, {x}, {y}, {z}, {vx}, {vy}, {vz}, and {q} set the
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attribute of a single atom, so the specified ID is an atom-ID number
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(1-N).
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Since atom attributes are assigned by the "read_data"_read_data.html,
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"read_restart"_read_restart.html or "create_atoms"_create_atoms.html
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commands, this command changes those assignments. This can be useful
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for altering pairwise and molecular force interactions, since
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force-field coefficients are defined in terms of types. It can also
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be used to change the labeling of atoms when they are output in
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"dump"_dump.html files. It can also be useful for debugging purposes;
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i.e. positioning an atom at a precise location to compute subsequent
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forces or energy.
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For style {atom}, the atom type of all atoms in the group is changed
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to the specified value from 1 to ntypes. Note that ntypes must be
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within the range the simulation was initialized for. The maximum
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number of types is set by the "create_box"_create_box.html command or
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the {atom types} field in the header of the data file read by the
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"read_data"_read_data.html command.
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For style {bond}, {angle}, {dihedral}, or {improper}, the bond type
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(angle type, etc) of all bonds (angles, etc) of atoms in the group is
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changed to the specified value from 1 to nbondtypes (angletypes, etc).
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All atoms in the bond (angle, etc) must be in the group in order for
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the change to be made. The maximum number of types is set by the
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{bond types} ({angle types}, etc) field in the header of the data
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file.
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For style {charge}, the charge of each atom in the group is set to
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the specified value.
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For style {dipole}, the specified value is used as a random number
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seed. The dipole moment of each atom in the group is set to a random
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orientation with a magnitude determined by the "dipole"_dipole.html
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command setting for that atom type.
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For styles {type}, {mol}, {x}, {y}, {z}, {vx}, {vy}, {vz}, or {q}, the
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corresponding attribute of a single atom with the specified atom-ID is
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set to the specified value. E.g. the last example above, sets the
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atom-type of atom 1492 to 3. If "type" were replaced by "q", the
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charge on atom 1492 would be set to 3; if it were replaced by "mol",
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then then the molecule-ID would be set to 3. The values for x,y,z are
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in distance units, the values for vx,vy,vz are in velocity units, and
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the value for charge is in charge units, as explained by the
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"units"_units.html command.
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[Restrictions:]
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This command requires inter-processor communication to coordinate the
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setting of bond types (angle types, etc). This means that your system
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must be ready to perform a simulation before using this command (force
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fields setup, atom masses set, etc). This is not necessary to simply
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reset atom types.
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You cannot set the {mol} or {q} for an atom if the
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"atom_style"_atom_style.html does not have those attributes.
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[Related commands:]
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"create_box"_create_box.html, "create_atoms"_create_atoms.html,
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"read_data"_read_data.html
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[Default:] none
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