# bond_style hybrid command

## Syntax

    bond_style hybrid style1 style2 ...

- style1,style2 = list of one or more bond styles

## Examples

    bond_style hybrid harmonic fene
    bond_coeff 1 harmonic 80.0 1.2
    bond_coeff 2* fene 30.0 1.5 1.0 1.0

## Description

The hybrid style enables the use of multiple bond styles in one simulation. A bond style is assigned to each bond type. For example, bonds in a polymer flow (of bond type 1) could be computed with a fene potential and bonds in the wall boundary (of bond type 2) could be computed with a harmonic potential. The assignment of bond type to style is made via the bond_coeff command or in the data file.

In the bond_coeff commands, the name of a bond style must be added after the bond type, with the remaining coefficients being those appropriate to that style. In the example above, the 2 bond_coeff commands set bonds of bond type 1 to be computed with a harmonic potential with coefficients 80.0, 1.2 for K, r0. All other bond types (2-N) are computed with a fene potential with coefficients 30.0, 1.5, 1.0, 1.0 for K, R0, epsilon, sigma.

If bond coefficients are specified in the data file read via the read_data command, then the same rule applies. E.g. “harmonic” or “fene” must be added after the bond type, for each line in the “Bond Coeffs” section, e.g.

    Bond Coeffs

    1 harmonic 80.0 1.2
    2 fene 30.0 1.5 1.0 1.0
    ...

A bond style of none with no additional coefficients can be used in place of a bond style, either in a input script bond_coeff command or in the data file, if you desire to turn off interactions for specific bond types.

## Restrictions

This bond style can only be used if LIGGGHTS(R)-PUBLIC was built with the MOLECULAR package (which it is by default). See the Making LIGGGHTS(R)-PUBLIC section for more info on packages.

Unlike other bond styles, the hybrid bond style does not store bond coefficient info for individual sub-styles in a binary restart files. Thus when retarting a simulation from a restart file, you need to re-specify bond_coeff commands.

## Related commands

bond_coeff, delete_bonds

Default: none