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<li>bond_coeff command</li>
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<div class="section" id="bond-coeff-command">
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<span id="index-0"></span><h1>bond_coeff command</h1>
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<div class="section" id="syntax">
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<h2>Syntax</h2>
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<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">bond_coeff</span> <span class="n">N</span> <span class="n">args</span>
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</pre></div>
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</div>
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<ul class="simple">
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<li>N = bond type (see asterisk form below)</li>
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<li>args = coefficients for one or more bond types</li>
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</ul>
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</div>
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<div class="section" id="examples">
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<h2>Examples</h2>
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<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">bond_coeff</span> <span class="mi">5</span> <span class="mf">80.0</span> <span class="mf">1.2</span>
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<span class="n">bond_coeff</span> <span class="o">*</span> <span class="mf">30.0</span> <span class="mf">1.5</span> <span class="mf">1.0</span> <span class="mf">1.0</span>
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<span class="n">bond_coeff</span> <span class="mi">1</span><span class="o">*</span><span class="mi">4</span> <span class="mf">30.0</span> <span class="mf">1.5</span> <span class="mf">1.0</span> <span class="mf">1.0</span>
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<span class="n">bond_coeff</span> <span class="mi">1</span> <span class="n">harmonic</span> <span class="mf">200.0</span> <span class="mf">1.0</span>
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</pre></div>
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</div>
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<div class="section" id="description">
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<h2>Description</h2>
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<p>Specify the bond force field coefficients for one or more bond types.
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The number and meaning of the coefficients depends on the bond style.
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Bond coefficients can also be set in the data file read by the
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<a class="reference internal" href="read_data.html"><span class="doc">read_data</span></a> command or in a restart file.</p>
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<p>N can be specified in one of two ways. An explicit numeric value can
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be used, as in the 1st example above. Or a wild-card asterisk can be
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used to set the coefficients for multiple bond types. This takes the
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form “*” or “<em>n” or “n</em>” or “m*n”. If N = the number of bond types,
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then an asterisk with no numeric values means all types from 1 to N. A
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leading asterisk means all types from 1 to n (inclusive). A trailing
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asterisk means all types from n to N (inclusive). A middle asterisk
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means all types from m to n (inclusive).</p>
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<p>Note that using a bond_coeff command can override a previous setting
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for the same bond type. For example, these commands set the coeffs
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for all bond types, then overwrite the coeffs for just bond type 2:</p>
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<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">bond_coeff</span> <span class="o">*</span> <span class="mf">100.0</span> <span class="mf">1.2</span>
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<span class="n">bond_coeff</span> <span class="mi">2</span> <span class="mf">200.0</span> <span class="mf">1.2</span>
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</pre></div>
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</div>
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<p>A line in a data file that specifies bond coefficients uses the exact
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same format as the arguments of the bond_coeff command in an input
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script, except that wild-card asterisks should not be used since
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coefficients for all N types must be listed in the file. For example,
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under the “Bond Coeffs” section of a data file, the line that
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corresponds to the 1st example above would be listed as</p>
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<div class="highlight-default"><div class="highlight"><pre><span></span><span class="mi">5</span> <span class="mf">80.0</span> <span class="mf">1.2</span>
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</pre></div>
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</div>
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<hr class="docutils" />
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<p>Here is an alphabetic list of bond styles defined in LAMMPS. Click on
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the style to display the formula it computes and coefficients
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specified by the associated <a class="reference internal" href="#"><span class="doc">bond_coeff</span></a> command.</p>
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<p>Note that here are also additional bond styles submitted by users
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which are included in the LAMMPS distribution. The list of these with
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links to the individual styles are given in the bond section of <a class="reference internal" href="Section_commands.html#cmd-5"><span class="std std-ref">this page</span></a>.</p>
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<ul class="simple">
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<li><a class="reference internal" href="bond_none.html"><span class="doc">bond_style none</span></a> - turn off bonded interactions</li>
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<li><a class="reference internal" href="bond_hybrid.html"><span class="doc">bond_style hybrid</span></a> - define multiple styles of bond interactions</li>
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<li><a class="reference internal" href="bond_class2.html"><span class="doc">bond_style class2</span></a> - COMPASS (class 2) bond</li>
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<li><a class="reference internal" href="bond_fene.html"><span class="doc">bond_style fene</span></a> - FENE (finite-extensible non-linear elastic) bond</li>
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<li><a class="reference internal" href="bond_fene_expand.html"><span class="doc">bond_style fene/expand</span></a> - FENE bonds with variable size particles</li>
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<li><a class="reference internal" href="bond_harmonic.html"><span class="doc">bond_style harmonic</span></a> - harmonic bond</li>
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<li><a class="reference internal" href="bond_morse.html"><span class="doc">bond_style morse</span></a> - Morse bond</li>
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<li><a class="reference internal" href="bond_nonlinear.html"><span class="doc">bond_style nonlinear</span></a> - nonlinear bond</li>
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<li><a class="reference internal" href="bond_quartic.html"><span class="doc">bond_style quartic</span></a> - breakable quartic bond</li>
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<li><a class="reference internal" href="bond_table.html"><span class="doc">bond_style table</span></a> - tabulated by bond length</li>
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</ul>
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</div>
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<hr class="docutils" />
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<div class="section" id="restrictions">
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<h2>Restrictions</h2>
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<p>This command must come after the simulation box is defined by a
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<a class="reference internal" href="read_data.html"><span class="doc">read_data</span></a>, <a class="reference internal" href="read_restart.html"><span class="doc">read_restart</span></a>, or
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<a class="reference internal" href="create_box.html"><span class="doc">create_box</span></a> command.</p>
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<p>A bond style must be defined before any bond coefficients are set,
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either in the input script or in a data file.</p>
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</div>
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<div class="section" id="related-commands">
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<h2>Related commands</h2>
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<p><a class="reference internal" href="bond_style.html"><span class="doc">bond_style</span></a></p>
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<p><strong>Default:</strong> none</p>
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