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bond_style command

Syntax:

bond_style style args 
  args = none for any style except hybrid
  hybrid args = list of one or more styles 

Examples:

bond_style harmonic
bond_style fene
bond_style hybrid harmonic fene 

Description:

Set the formula(s) LAMMPS uses to compute bond interactions between pairs of atoms. In LAMMPS, a bond differs from a pairwise interaction, which are set via the pair_style command. Bonds are defined between specified pairs of atoms and remain in force for the duration of the simulation (unless the bond breaks which is possible in some bond potentials). The list of bonded atoms is read in by a read_data or read_restart command from a data or restart file. By contrast, pair potentials are defined between pairs of atoms that are within a cutoff distance and the set of active interactions typically changes over time.

Hybrid models where bonds are computed using different bond potentials can be setup using the hybrid bond style.

The coefficients associated with a bond style can be specified in a data or restart file or via the bond_coeff command.

In the formulas listed for each bond style, r is the distance between the 2 atoms in the bond.

Note that when both a bond and pair style is defined, the special_bond command often needs to be used to turn off (or weight) the pairwise interaction that would otherwise exist between 2 bonded atoms.


Here is an alphabetic list of bond styles defined in LAMMPS. Click on the style to display the formula it computes and coefficients specified by the associated bond_coeff command:


Restrictions:

Bond styles can only be set for atom styles that allow bonds to be defined.

Bond styles are part of the "molecular" package or other packages as noted in their documentation. They are only enabled if LAMMPS was built with that package. See the Making LAMMPS section for more info.

Related commands:

bond_coeff, delete_bonds

Default:

bond_style none