\(\renewcommand{\AA}{\text{Å}}\)

# fix eos/cv command

## Syntax

    fix ID group-ID eos/cv cv

- ID, group-ID are documented in fix command

- eos/cv = style name of this fix command

- cv = constant-volume heat capacity (energy/temperature units)

## Examples

    fix 1 all eos/cv 0.01

## Description

Fix eos/cv applies a mesoparticle equation of state to relate the particle internal energy (\(u_i\)) to the particle internal temperature (\(\theta_i\)). The eos/cv mesoparticle equation of state requires the constant-volume heat capacity, and is defined as follows:

\[u_{i} = u^{mech}_{i} + u^{cond}_{i} = C_{V} \theta_{i}\]

where \(C_V\) is the constant-volume heat capacity, \(u^{cond}\) is the internal conductive energy, and \(u^{mech}\) is the internal mechanical energy. Note that alternative definitions of the mesoparticle equation of state are possible.

## Restrictions

This command is part of the DPD-REACT package. It is only enabled if LAMMPS was built with that package. See the Build package page for more info.

This command also requires use of the atom_style dpd command.

## Related commands

fix shardlow, pair dpd/fdt

## Default

none

(Larentzos) J.P. Larentzos, J.K. Brennan, J.D. Moore, and W.D. Mattson, “LAMMPS Implementation of Constant Energy Dissipative Particle Dynamics (DPD-E)”, ARL-TR-6863, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD (2014).