88 lines
2.3 KiB
ReStructuredText
88 lines
2.3 KiB
ReStructuredText
.. index:: compute dpd
|
|
|
|
compute dpd command
|
|
===================
|
|
|
|
Syntax
|
|
""""""
|
|
|
|
.. parsed-literal::
|
|
|
|
compute ID group-ID dpd
|
|
|
|
* ID, group-ID are documented in :doc:`compute <compute>` command
|
|
* dpd = style name of this compute command
|
|
|
|
Examples
|
|
""""""""
|
|
|
|
.. code-block:: LAMMPS
|
|
|
|
compute 1 all dpd
|
|
|
|
Description
|
|
"""""""""""
|
|
|
|
Define a computation that accumulates the total internal conductive
|
|
energy (:math:`U^{cond}`), the total internal mechanical energy
|
|
(:math:`U^{mech}`), the total chemical energy (:math:`U^{chem}`)
|
|
and the *harmonic* average of the internal temperature (:math:`\theta_{avg}`)
|
|
for the entire system of particles. See the
|
|
:doc:`compute dpd/atom <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:
|
|
|
|
.. math::
|
|
|
|
U^{cond} = & \displaystyle\sum_{i=1}^{N} u_{i}^{cond} \\
|
|
U^{mech} = & \displaystyle\sum_{i=1}^{N} u_{i}^{mech} \\
|
|
U^{chem} = & \displaystyle\sum_{i=1}^{N} u_{i}^{chem} \\
|
|
U = & \displaystyle\sum_{i=1}^{N} (u_{i}^{cond} + u_{i}^{mech} + u_{i}^{chem}) \\
|
|
\theta_{avg} = & (\frac{1}{N}\displaystyle\sum_{i=1}^{N} \frac{1}{\theta_{i}})^{-1} \\
|
|
|
|
where :math:`N` is the number of particles in the system
|
|
|
|
----------
|
|
|
|
Output info
|
|
"""""""""""
|
|
|
|
This compute calculates a global vector of length 5 (:math:`U^{cond}`,
|
|
:math:`U^{mech}`, :math:`U^{chem}`, :math:`\theta_{avg}`, :math:`N`),
|
|
which can be accessed by indices 1-5.
|
|
See the :doc:`Howto output <Howto_output>` page for an overview of
|
|
LAMMPS output options.
|
|
|
|
The vector values will be in energy and temperature :doc:`units <units>`.
|
|
|
|
Restrictions
|
|
""""""""""""
|
|
|
|
This command is part of the DPD-REACT package. It is only enabled if
|
|
LAMMPS was built with that package. See the :doc:`Build package <Build_package>` page for more info.
|
|
|
|
This command also requires use of the :doc:`atom_style dpd <atom_style>`
|
|
command.
|
|
|
|
Related commands
|
|
""""""""""""""""
|
|
|
|
:doc:`compute dpd/atom <compute_dpd_atom>`,
|
|
:doc:`thermo_style <thermo_style>`
|
|
|
|
Default
|
|
"""""""
|
|
|
|
none
|
|
|
|
----------
|
|
|
|
.. _Larentzos1:
|
|
|
|
**(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).
|