80 lines
2.6 KiB
ReStructuredText
80 lines
2.6 KiB
ReStructuredText
.. index:: bond_write
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bond_write command
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==================
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Syntax
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""""""
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.. code-block:: LAMMPS
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bond_write btype N inner outer file keyword itype jtype
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* btype = bond type
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* N = # of values
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* inner,outer = inner and outer bond length (distance units)
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* file = name of file to write values to
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* keyword = section name in file for this set of tabulated values
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* itype,jtype = 2 atom types (optional)
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Examples
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""""""""
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.. code-block:: LAMMPS
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bond_write 1 500 0.5 3.5 table.txt Harmonic_1
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bond_write 3 1000 0.1 6.0 table.txt Morse
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Description
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"""""""""""
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Write energy and force values to a file as a function of distance for
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the currently defined :doc:`bond style <bond_style>` for a selected bond
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type. This is useful for plotting the potential function or otherwise
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debugging its values. The resulting file can also be used as input for
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use with :doc:`bond style table <bond_table>`.
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If the file already exists, the table of values is appended to the end
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of the file to allow multiple tables of energy and force to be included
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in one file. The individual sections may be identified by the *keyword*.
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The energy and force values are computed at distances from *inner* to
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*outer* for 2 interacting atoms forming a bond of type *btype*, using
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the appropriate :doc:`bond_coeff <bond_coeff>` coefficients. N evenly
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spaced distances are used.
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For example, for N = 7, inner = 1.0, and outer = 4.0,
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values are computed at r = 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0.
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The file is written in the format used as input for the :doc:`bond_style
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table <bond_table>` option with *keyword* as the section name. Each
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line written to the file lists an index number (1-N), a distance (in
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distance units), an energy (in energy units), and a force (in force
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units). In case a new file is created, the first line will be a comment
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with a "DATE:" and "UNITS:" tag with the current date and :doc:`units
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<units>` settings. For subsequent invocations of the *bond_write*
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command for the same file, data will be appended and the current units
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settings will be compared to the data from the header, if present. The
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*bond_write* command will refuse to add a table to an existing file if
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the units are not the same.
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Restrictions
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""""""""""""
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All force field coefficients for bond and other kinds of interactions
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must be set before this command can be invoked.
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Due to how the bond force is computed, an inner value > 0.0 must
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be specified even if the potential has a finite value at r = 0.0.
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Related commands
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""""""""""""""""
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:doc:`bond_style table <bond_table>`, :doc:`angle_write <angle_write>`,
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:doc:`bond_style <bond_style>`, :doc:`bond_coeff <bond_coeff>`
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Default
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"""""""
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none
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