74 lines
2.4 KiB
ReStructuredText
74 lines
2.4 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 types
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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 bond potential. This is useful for plotting the
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potential function or otherwise debugging its values. If the file
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already exists, the table of values is appended to the end of the file
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to allow multiple tables of energy and force to be included in one
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file.
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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 the
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appropriate :doc:`bond_coeff <bond_coeff>` coefficients. N evenly spaced
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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
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:doc:`bond_style <bond_style>` *table* option with *keyword* as the
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section name. Each line written to the file lists an index number
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(1-N), a distance (in distance units), an energy (in energy units),
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and a force (in force units). In case a new file is created, the first
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line will be a comment with a "DATE:" and "UNITS:" tag with the current
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date and :doc:`units <units>` settings. For subsequent invocations of
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the bond_write command for the same file, data will be appended and the
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current units settings will be compared to the data from the header, if
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present, and bond_write will refuse to add a table if the units are not
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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>`,
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:doc:`bond_style <bond_style>`, :doc:`bond_coeff <bond_coeff>`
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**Default:** none
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