# compute improper command

## Syntax

``` LAMMPS
compute ID group-ID improper
```

-   ID, group-ID are documented in [compute](compute) command
-   improper = style name of this compute command

## Examples

``` LAMMPS
compute 1 all improper
```

## Description

Define a computation that extracts the improper energy calculated by
each of the improper sub-styles used in the [improper_style
hybrid](improper_hybrid) command. These values are made accessible for
output or further processing by other commands. The group specified for
this command is ignored.

This compute is useful when using [improper_style
hybrid](improper_hybrid) if you want to know the portion of the total
energy contributed by one or more of the hybrid sub-styles.

## Output info

This compute calculates a global vector of length $N$, where $N$ is the
number of sub_styles defined by the [improper_style
hybrid](improper_style) command. These styles can be accessed by the
indices 1 through $N$. These values can be used by any command that uses
global scalar or vector values from a compute as input. See the [Howto
output](Howto_output) page for an overview of LAMMPS output options.

The vector values are \"extensive\" and will be in energy
[units](units).

## Restrictions

> none

## Related commands

[compute pe](compute_pe), [compute pair](compute_pair)

## Default

none