"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Commands_all.html)

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bond_coeff command :h3

[Syntax:]

bond_coeff N args :pre

N = bond type (see asterisk form below)
args = coefficients for one or more bond types :ul

[Examples:]

bond_coeff 5 80.0 1.2
bond_coeff * 30.0 1.5 1.0 1.0
bond_coeff 1*4 30.0 1.5 1.0 1.0
bond_coeff 1 harmonic 200.0 1.0 :pre

[Description:]

Specify the bond force field coefficients for one or more bond types.
The number and meaning of the coefficients depends on the bond style.
Bond coefficients can also be set in the data file read by the
"read_data"_read_data.html command or in a restart file.

N can be specified in one of two ways.  An explicit numeric value can
be used, as in the 1st example above.  Or a wild-card asterisk can be
used to set the coefficients for multiple bond types.  This takes the
form "*" or "*n" or "n*" or "m*n".  If N = the number of bond types,
then an asterisk with no numeric values means all types from 1 to N.  A
leading asterisk means all types from 1 to n (inclusive).  A trailing
asterisk means all types from n to N (inclusive).  A middle asterisk
means all types from m to n (inclusive).

Note that using a bond_coeff command can override a previous setting
for the same bond type.  For example, these commands set the coeffs
for all bond types, then overwrite the coeffs for just bond type 2:

bond_coeff * 100.0 1.2
bond_coeff 2 200.0 1.2 :pre

A line in a data file that specifies bond coefficients uses the exact
same format as the arguments of the bond_coeff command in an input
script, except that wild-card asterisks should not be used since
coefficients for all N types must be listed in the file.  For example,
under the "Bond Coeffs" section of a data file, the line that
corresponds to the 1st example above would be listed as

5 80.0 1.2 :pre

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The list of all bond styles defined in LAMMPS is given on the
"bond_style"_bond_style.html doc page.  They are also listed in more
compact form on the "Commands bond"_Commands_bond.html doc page.

On either of those pages, click on the style to display the formula it
computes and its coefficients as specified by the associated
bond_coeff command.

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[Restrictions:]

This command must come after the simulation box is defined by a
"read_data"_read_data.html, "read_restart"_read_restart.html, or
"create_box"_create_box.html command.

A bond style must be defined before any bond coefficients are set,
either in the input script or in a data file.

[Related commands:]

"bond_style"_bond_style.html

[Default:] none
