# fix heat/flow command

## Syntax

    fix ID group-ID heat/flow style values ...

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

-   heat/flow = style name of this fix command

-   one style with corresponding value(s) needs to be listed

        style = *constant* or *type*
          *constant* = cp
            cp = value of specifc heat (energy/(mass * temperature) units)
          *type* = cp1 ... cpN
            cpN = value of specifc heat for type N (energy/(mass * temperature) units)

-   

## Examples

``` LAMMPS
fix 1 all heat/flow constant 1.0
fix 1 all heat/flow type 1.0 0.5
```

## Description

Perform plain time integration to update temperature for atoms in the
group each timestep. The specific heat of atoms can be defined using
either the *constant* or *type* keywords. For style *constant*, the
specific heat is a constant value *cp* for all atoms. For style *type*,
*N* different values of the specific heat are defined, one for each of
the *N* types of atoms.

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## Restart, fix_modify, output, run start/stop, minimize info

No information about this fix is written to [binary restart
files](restart). None of the [fix_modify](fix_modify) options are
relevant to this fix. No global or per-atom quantities are stored by
this fix for access by various [output commands](Howto_output). No
parameter of this fix can be used with the *start/stop* keywords of the
[run](run) command. This fix is not invoked during [energy
minimization](minimize).

## Restrictions

This fix requires that atoms store temperature and heat flow as defined
by the [fix property/atom](fix_property_atom) command.

## Related commands

[pair granular](pair_granular), [fix property/atom](fix_property_atom)

## Default

none