# 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 (dpdTheta_i). The eos/cv mesoparticle equation of state requires the constant-volume heat capacity, and is defined as follows:

where Cv 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 Making LAMMPS section for more info.

This command also requires use of the atom_style dpd command.