# compute efield/atom command

## Syntax

``` LAMMPS
compute ID group-ID efield/atom keyword val
```

-   ID, group-ID are documented in [compute](compute) command

-   efield/atom = style name of this compute command

-   zero or more keyword/value pairs may be appended

-   keyword = *pair* or *kspace*

        *pair* args = *yes* or *no*
        *kspace* args = *yes* or *no*

## Examples

``` LAMMPS
compute 1 all efield/atom
compute 1 all efield/atom pair yes kspace no
```

Used in input scripts:

    examples/PACKAGES/dielectric/in.confined
    examples/PACKAGES/dielectric/in.nopbc

## Description

Define a computation that calculates the electric field at each atom in
a group. The compute should only enabled with pair and kspace styles
that are provided by the DIELECTRIC package because only these styles
compute the per-atom electric field at every time step.

The electric field is a 3-component vector. The value of the electric
field components will be 0.0 for atoms not in the specified compute
group.

------------------------------------------------------------------------

The keyword/value option pairs are used in the following ways.

For the *pair* and *kspace* keywords, the real-space and
reciprocal-space contributions to the electric field can be turned off
and on.

## Output info

This compute calculates a per-atom vector, which can be accessed by any
command that uses per-atom values from a compute as input. See the
[Howto output](Howto_output) page for an overview of LAMMPS output
options.

The per-atom vector values will be in electric field [units](units).

## Restrictions

This compute is part of the DIELECTRIC package. It is only enabled if
LAMMPS was built with that package.

## Related commands

[dump custom](dump)

## Default

The option defaults are pair = yes and kspace = yes.