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compute_ke_atom_eff.txt
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.. index:: compute ke/atom/eff
compute ke/atom/eff command
===========================
Syntax
""""""
.. parsed-literal::
compute ID group-ID ke/atom/eff
* ID, group-ID are documented in :doc:`compute <compute>` command
* ke/atom/eff = style name of this compute command
Examples
""""""""
.. parsed-literal::
compute 1 all ke/atom/eff
Description
"""""""""""
Define a computation that calculates the per-atom translational
(nuclei and electrons) and radial kinetic energy (electron only) in a
group. The particles are assumed to be nuclei and electrons modeled
with the :doc:`electronic force field <pair_eff>`.
The kinetic energy for each nucleus is computed as 1/2 m v^2, where m
corresponds to the corresponding nuclear mass, and the kinetic energy
for each electron is computed as 1/2 (me v^2 + 3/4 me s^2), where me
and v correspond to the mass and translational velocity of each
electron, and s to its radial velocity, respectively.
There is a subtle difference between the quantity calculated by this
compute and the kinetic energy calculated by the *ke* or *etotal*
keyword used in thermodynamic output, as specified by the
:doc:`thermo_style <thermo_style>` command. For this compute, kinetic
energy is "translational" plus electronic "radial" kinetic energy,
calculated by the simple formula above. For thermodynamic output, the
*ke* keyword infers kinetic energy from the temperature of the system
with 1/2 Kb T of energy for each (nuclear-only) degree of freedom in
eFF.
.. note::
The temperature in eFF should be monitored via the :doc:`compute temp/eff <compute_temp_eff>` command, which can be printed with
thermodynamic output by using the :doc:`thermo_modify <thermo_modify>`
command, as shown in the following example:
.. parsed-literal::
compute effTemp all temp/eff
thermo_style custom step etotal pe ke temp press
thermo_modify temp effTemp
The value of the kinetic energy will be 0.0 for atoms (nuclei or
electrons) not in the specified compute group.
**Output info:**
This compute calculates a scalar quantity for each atom, which can be
accessed by any command that uses per-atom computes as input. See
:ref:`Section_howto 15 <howto_15>` for an overview of
LAMMPS output options.
The per-atom vector values will be in energy :doc:`units <units>`.
Restrictions
""""""""""""
This compute is part of the USER-EFF package. It is only enabled if
LAMMPS was built with that package. See the :ref:`Making LAMMPS <start_3>` section for more info.
Related commands
""""""""""""""""
:doc:`dump custom <dump>`
**Default:** none
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm
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