# 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 USER-DPD package. It is only enabled if LAMMPS was built with that package. See the Build package doc page for more info.

This command also requires use of the atom_style dpd command.

## 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).