<h2>Restart, fix_modify, output, run start/stop, minimize info<aclass="headerlink"href="#restart-fix-modify-output-run-start-stop-minimize-info"title="Permalink to this headline">¶</a></h2>
<p>No information about this fix is written to <aclass="reference internal"href="restart.html"><em>binary restart files</em></a>.</p>
<p>The <aclass="reference internal"href="fix_modify.html"><em>fix_modify</em></a><em>energy</em> option is supported by this
fix to add the energy stored in the spring to the system’s potential
energy as part of <aclass="reference internal"href="thermo_style.html"><em>thermodynamic output</em></a>.</p>
<p>This fix computes a global scalar which can be accessed by various
<aclass="reference internal"href="Section_howto.html#howto-15"><span>output commands</span></a>. The scalar is the
spring energy = 0.5 * K * r^2.</p>
<p>This fix also computes global 4-vector which can be accessed by
various <aclass="reference internal"href="Section_howto.html#howto-15"><span>output commands</span></a>. The first 3
quantities in the vector are xyz components of the total force added
to the group of atoms by the spring. In the case of the <em>couple</em>
style, it is the force on the fix group (group-ID) or the negative of
the force on the 2nd group (group-ID2). The 4th quantity in the
vector is the magnitude of the force added by the spring, as a
positive value if (r-R0) > 0 and a negative value if (r-R0) < 0. This
sign convention can be useful when using the spring force to compute a
potential of mean force (PMF).</p>
<p>The scalar and vector values calculated by this fix are “extensive”.</p>
<p>No parameter of this fix can be used with the <em>start/stop</em> keywords of
the <aclass="reference internal"href="run.html"><em>run</em></a> command.</p>
<p>The forces due to this fix are imposed during an energy minimization,
invoked by the <aclass="reference internal"href="minimize.html"><em>minimize</em></a> command.</p>
<divclass="admonition note">
<pclass="first admonition-title">Note</p>
<pclass="last">If you want the spring energy to be included in the total
potential energy of the system (the quantity being minimized), you
MUST enable the <aclass="reference internal"href="fix_modify.html"><em>fix_modify</em></a><em>energy</em> option for this
fix.</p>
</div>
</div>
<divclass="section"id="restrictions">
<h2>Restrictions<aclass="headerlink"href="#restrictions"title="Permalink to this headline">¶</a></h2>
<blockquote>
<div>none</div></blockquote>
</div>
<divclass="section"id="related-commands">
<h2>Related commands<aclass="headerlink"href="#related-commands"title="Permalink to this headline">¶</a></h2>
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