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lammps/doc/_sources/bond_harmonic_shift.txt
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bond_harmonic_shift.txt
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.. index:: bond_style harmonic/shift
bond_style harmonic/shift command
=================================
bond_style harmonic/shift/omp command
=====================================
Syntax
""""""
.. parsed-literal::
bond_style harmonic/shift
Examples
""""""""
.. parsed-literal::
bond_style harmonic/shift
bond_coeff 5 10.0 0.5 1.0
Description
"""""""""""
The *harmonic/shift* bond style is a shifted harmonic bond that uses
the potential
.. image:: Eqs/bond_harmonic_shift.jpg
:align: center
where r0 is the equilibrium bond distance, and rc the critical distance.
The potential is -Umin at r0 and zero at rc. The spring constant is
k = Umin / [ 2 (r0-rc)^2].
The following coefficients must be defined for each bond type via the
:doc:`bond_coeff <bond_coeff>` command as in the example above, or in
the data file or restart files read by the :doc:`read_data <read_data>`
or :doc:`read_restart <read_restart>` commands:
* Umin (energy)
* r0 (distance)
* rc (distance)
----------
Styles with a *cuda*, *gpu*, *intel*, *kk*, *omp*, or *opt* suffix are
functionally the same as the corresponding style without the suffix.
They have been optimized to run faster, depending on your available
hardware, as discussed in :doc:`Section_accelerate <Section_accelerate>`
of the manual. The accelerated styles take the same arguments and
should produce the same results, except for round-off and precision
issues.
These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
KOKKOS, USER-OMP and OPT packages, respectively. They are only
enabled if LAMMPS was built with those packages. See the :ref:`Making LAMMPS <start_3>` section for more info.
You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the :ref:`-suffix command-line switch <start_7>` when you invoke LAMMPS, or you can
use the :doc:`suffix <suffix>` command in your input script.
See :doc:`Section_accelerate <Section_accelerate>` of the manual for
more instructions on how to use the accelerated styles effectively.
----------
Restrictions
""""""""""""
This bond style can only be used if LAMMPS was built with the
USER-MISC package. See the :ref:`Making LAMMPS <start_3>`
section for more info on packages.
Related commands
""""""""""""""""
:doc:`bond_coeff <bond_coeff>`, :doc:`delete_bonds <delete_bonds>`,
:doc:`bond_harmonic <bond_harmonic>`
**Default:** none
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm
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