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compute dpd command

Syntax

compute ID group-ID dpd

• ID, group-ID are documented in compute command

• dpd = style name of this compute command

Examples

compute 1 all dpd

Description

Define a computation that accumulates the total internal conductive energy ($U^{\text{cond}}$), the total internal mechanical energy ($U^{\text{mech}}$), the total chemical energy ($U^{\text{chem}}$) and the harmonic average of the internal temperature (${\theta }_{\text{avg}}$) for the entire system of particles. See the compute dpd/atom command if you want per-particle internal energies and internal temperatures.

The system internal properties are computed according to the following relations:

$$\begin{array}{rl}{U}^{\text{cond}}=& \sum _{i=1}^N{u}_i^{\text{cond}}\\ U^{\text{mech}}=& \sum _{i=1}^N{u}_i^{\text{mech}}\\ U^{\text{chem}}=& \sum _{i=1}^N{u}_i^{\text{chem}}\\ U=& \sum _{i=1}^N(u_i^{\text{cond}}+u_i^{\text{mech}}+u_i^{\text{chem}})\\ {\theta }_{avg}=& (\frac{1}{N}\sum _{i=1}^N\frac{1}{{\theta }_i}{)}^{-1}\end{array}$$

where $N$ is the number of particles in the system.

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Output info

This compute calculates a global vector of length 5 ($U^{\text{cond}}$, $U^{\text{mech}}$, $U^{\text{chem}}$, ${\theta }_{\text{avg}}$, $N$), which can be accessed by indices 1 through 5. See the Howto output page for an overview of LAMMPS output options.

The vector values will be in energy and temperature units.

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

compute dpd/atom, thermo_style

Default

none

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(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).