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<div class="section" id="fix-freeze-command">
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<span id="index-0"></span><h1>fix freeze command<a class="headerlink" href="#fix-freeze-command" title="Permalink to this headline">¶</a></h1>
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<div class="section" id="fix-freeze-cuda-command">
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<h1>fix freeze/cuda command<a class="headerlink" href="#fix-freeze-cuda-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>fix ID group-ID freeze
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</pre></div>
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</div>
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<ul class="simple">
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<li>ID, group-ID are documented in <a class="reference internal" href="fix.html"><em>fix</em></a> command</li>
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<li>freeze = style name of this fix command</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>fix 2 bottom freeze
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</pre></div>
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</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>Zero out the force and torque on a granular particle. This is useful
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for preventing certain particles from moving in a simulation. The
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<a class="reference internal" href="pair_gran.html"><em>granular pair styles</em></a> also detect if this fix has been
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defined and compute interactions between frozen and non-frozen
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particles appropriately, as if the frozen particle has infinite mass.
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A similar functionality for normal (point) particles can be obtained
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using <a class="reference internal" href="fix_setforce.html"><em>fix setforce</em></a>.</p>
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<hr class="docutils" />
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<p>Styles with a <em>cuda</em> suffix are functionally the same as the
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corresponding style without the suffix. They have been optimized to
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run faster, depending on your available hardware, as discussed in
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<a class="reference internal" href="Section_accelerate.html"><em>Section_accelerate</em></a> of the manual. The
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accelerated styles take the same arguments and should produce the same
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results, except for round-off and precision issues.</p>
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<p>These accelerated styles are part of the USER-CUDA package. They are
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only enabled if LAMMPS was built with that package. See the <a class="reference internal" href="Section_start.html#start-3"><span>Making LAMMPS</span></a> section for more info.</p>
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<p>You can specify the accelerated styles explicitly in your input script
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by including their suffix, or you can use the <a class="reference internal" href="Section_start.html#start-7"><span>-suffix command-line switch</span></a> when you invoke LAMMPS, or you can
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use the <a class="reference internal" href="suffix.html"><em>suffix</em></a> command in your input script.</p>
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<p>See <a class="reference internal" href="Section_accelerate.html"><em>Section_accelerate</em></a> of the manual for
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more instructions on how to use the accelerated styles effectively.</p>
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</div>
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<hr class="docutils" />
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<div class="section" id="restart-fix-modify-output-run-start-stop-minimize-info">
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<h2>Restart, fix_modify, output, run start/stop, minimize info<a class="headerlink" href="#restart-fix-modify-output-run-start-stop-minimize-info" title="Permalink to this headline">¶</a></h2>
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<p>No information about this fix is written to <a class="reference internal" href="restart.html"><em>binary restart files</em></a>. None of the <a class="reference internal" href="fix_modify.html"><em>fix_modify</em></a> options
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are relevant to this fix.</p>
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<p>This fix computes a global 3-vector of forces, which can be accessed
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by various <a class="reference internal" href="Section_howto.html#howto-15"><span>output commands</span></a>. This is the
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total force on the group of atoms before the forces on individual
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atoms are changed by the fix. The vector values calculated by this
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fix are “extensive”.</p>
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<p>No parameter of this fix can be used with the <em>start/stop</em> keywords of
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the <a class="reference internal" href="run.html"><em>run</em></a> command. This fix is not invoked during <a class="reference internal" href="minimize.html"><em>energy minimization</em></a>.</p>
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</div>
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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 fix is part of the GRANULAR package. It is only enabled if
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LAMMPS was built with that package. See the <a class="reference internal" href="Section_start.html#start-3"><span>Making LAMMPS</span></a> section for more info.</p>
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<p>There can only be a single freeze fix defined. This is because other
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the <a class="reference internal" href="pair_gran.html"><em>granular pair styles</em></a> treat frozen particles
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differently and need to be able to reference a single group to which
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this fix is applied.</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="atom_style.html"><em>atom_style sphere</em></a>, <a class="reference internal" href="fix_setforce.html"><em>fix setforce</em></a></p>
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<p><strong>Default:</strong> none</p>
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