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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<a class="headerlink" href="#bond-coeff-command" title="Permalink to this headline">¶</a></h1>
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<div class="section" id="syntax">
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<h2>Syntax<a class="headerlink" href="#syntax" title="Permalink to this headline">¶</a></h2>
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<div class="highlight-python"><div class="highlight"><pre>bond_coeff N args
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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<a class="headerlink" href="#examples" title="Permalink to this headline">¶</a></h2>
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<div class="highlight-python"><div class="highlight"><pre>bond_coeff 5 80.0 1.2
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bond_coeff * 30.0 1.5 1.0 1.0
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bond_coeff 1*4 30.0 1.5 1.0 1.0
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bond_coeff 1 harmonic 200.0 1.0
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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<a class="headerlink" href="#description" title="Permalink to this headline">¶</a></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"><em>read_data</em></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-python"><div class="highlight"><pre>bond_coeff * 100.0 1.2
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bond_coeff 2 200.0 1.2
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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-python"><div class="highlight"><pre>5 80.0 1.2
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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=""><em>bond_coeff</em></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>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"><em>bond_style none</em></a> - turn off bonded interactions</li>
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<li><a class="reference internal" href="bond_hybrid.html"><em>bond_style hybrid</em></a> - define multiple styles of bond interactions</li>
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<li><a class="reference internal" href="bond_class2.html"><em>bond_style class2</em></a> - COMPASS (class 2) bond</li>
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<li><a class="reference internal" href="bond_fene.html"><em>bond_style fene</em></a> - FENE (finite-extensible non-linear elastic) bond</li>
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<li><a class="reference internal" href="bond_fene_expand.html"><em>bond_style fene/expand</em></a> - FENE bonds with variable size particles</li>
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<li><a class="reference internal" href="bond_harmonic.html"><em>bond_style harmonic</em></a> - harmonic bond</li>
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<li><a class="reference internal" href="bond_morse.html"><em>bond_style morse</em></a> - Morse bond</li>
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<li><a class="reference internal" href="bond_nonlinear.html"><em>bond_style nonlinear</em></a> - nonlinear bond</li>
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<li><a class="reference internal" href="bond_quartic.html"><em>bond_style quartic</em></a> - breakable quartic bond</li>
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<li><a class="reference internal" href="bond_table.html"><em>bond_style table</em></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<a class="headerlink" href="#restrictions" title="Permalink to this headline">¶</a></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"><em>read_data</em></a>, <a class="reference internal" href="read_restart.html"><em>read_restart</em></a>, or
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<a class="reference internal" href="create_box.html"><em>create_box</em></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<a class="headerlink" href="#related-commands" title="Permalink to this headline">¶</a></h2>
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<p><a class="reference internal" href="bond_style.html"><em>bond_style</em></a></p>
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<p><strong>Default:</strong> none</p>
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