\(\renewcommand{\AA}{\text{Å}}\)

# angle_style hybrid command

## Syntax

```
angle_style hybrid style1 style2 ...
```

style1,style2 = list of one or more angle styles

## Examples

```
angle_style hybrid harmonic cosine
angle_coeff 1 harmonic 80.0 30.0
angle_coeff 2* cosine 50.0
```

## Description

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

In the angle_coeff commands, the name of an angle style must be added
after the angle type, with the remaining coefficients being those
appropriate to that style. In the example above, the 2 angle_coeff
commands set angles of angle type 1 to be computed with a *harmonic*
potential with coefficients 80.0, 30.0 for \(K\), \(\theta_0\). All other angle
types \((2 - N)\) are computed with a *cosine* potential with coefficient
50.0 for \(K\).

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

```
Angle Coeffs
1 harmonic 80.0 30.0
2 cosine 50.0
...
```

If *class2* is one of the angle hybrid styles, the same rule holds for
specifying additional BondBond (and BondAngle) coefficients either via
the input script or in the data file. I.e. *class2* must be added to
each line after the angle type. For lines in the BondBond (or
BondAngle) section of the data file for angle types that are not
*class2*, you must use an angle style of *skip* as a placeholder, e.g.

```
BondBond Coeffs
1 skip
2 class2 3.6512 1.0119 1.0119
...
```

Note that it is not necessary to use the angle style *skip* in the
input script, since BondBond (or BondAngle) coefficients need not be
specified at all for angle types that are not *class2*.

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

## Restrictions

This angle style can only be used if LAMMPS was built with the MOLECULE package. See the Build package doc page for more info.

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

## Default

none