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<div class="section" id="fix-store-state-command">
<span id="index-0"></span><h1>fix store/state command<a class="headerlink" href="#fix-store-state-command" title="Permalink to this headline"></a></h1>
<div class="section" id="syntax">
<h2>Syntax<a class="headerlink" href="#syntax" title="Permalink to this headline"></a></h2>
<div class="highlight-python"><div class="highlight"><pre>fix ID group-ID store/state N input1 input2 ... keyword value ...
</pre></div>
</div>
<ul class="simple">
<li>ID, group-ID are documented in <a class="reference internal" href="fix.html"><em>fix</em></a> command</li>
<li>store/state = style name of this fix command</li>
<li>N = store atom attributes every N steps, N = 0 for initial store only</li>
<li>input = one or more atom attributes</li>
</ul>
<div class="highlight-python"><div class="highlight"><pre>possible attributes = id, mol, type, mass,
x, y, z, xs, ys, zs, xu, yu, zu, ix, iy, iz,
vx, vy, vz, fx, fy, fz,
q, mux, muy, muz,
radius, omegax, omegay, omegaz,
angmomx, angmomy, angmomz, tqx, tqy, tqz,
c_ID, c_ID[N], f_ID, f_ID[N], v_name,
d_name, i_name
</pre></div>
</div>
<div class="highlight-python"><div class="highlight"><pre>id = atom ID
mol = molecule ID
type = atom type
mass = atom mass
x,y,z = unscaled atom coordinates
xs,ys,zs = scaled atom coordinates
xu,yu,zu = unwrapped atom coordinates
ix,iy,iz = box image that the atom is in
vx,vy,vz = atom velocities
fx,fy,fz = forces on atoms
q = atom charge
mux,muy,muz = orientation of dipolar atom
radius = radius of spherical particle
omegax,omegay,omegaz = angular velocity of spherical particle
angmomx,angmomy,angmomz = angular momentum of aspherical particle
tqx,tqy,tqz = torque on finite-size particles
c_ID = per-atom vector calculated by a compute with ID
c_ID[I] = Ith column of per-atom array calculated by a compute with ID
f_ID = per-atom vector calculated by a fix with ID
f_ID[I] = Ith column of per-atom array calculated by a fix with ID
v_name = per-atom vector calculated by an atom-style variable with name
d_name = per-atom floating point vector name, managed by fix property/atom
i_name = per-atom integer vector name, managed by fix property/atom
</pre></div>
</div>
<ul class="simple">
<li>zero or more keyword/value pairs may be appended</li>
<li>keyword = <em>com</em></li>
</ul>
<pre class="literal-block">
<em>com</em> value = <em>yes</em> or <em>no</em>
</pre>
</div>
<div class="section" id="examples">
<h2>Examples<a class="headerlink" href="#examples" title="Permalink to this headline"></a></h2>
<div class="highlight-python"><div class="highlight"><pre>fix 1 all store/state 0 x y z
fix 1 all store/state 0 xu yu zu com yes
fix 2 all store/state 1000 vx vy vz
</pre></div>
</div>
</div>
<div class="section" id="description">
<h2>Description<a class="headerlink" href="#description" title="Permalink to this headline"></a></h2>
<p>Define a fix that stores attributes for each atom in the group at the
time the fix is defined. If <em>N</em> is 0, then the values are never
updated, so this is a way of archiving an atom attribute at a given
time for future use in a calculation or output. See the discussion of
<a class="reference internal" href="Section_howto.html#howto-15"><span>output commands</span></a> that take fixes as
inputs. And see for example, the <a class="reference internal" href="compute_reduce.html"><em>compute reduce</em></a>, <a class="reference internal" href="fix_ave_atom.html"><em>fix ave/atom</em></a>, <a class="reference internal" href="fix_ave_histo.html"><em>fix ave/histo</em></a>, <a class="reference internal" href="fix_ave_spatial.html"><em>fix ave/spatial</em></a>,
and <a class="reference internal" href="variable.html"><em>atom-style variable</em></a> commands.</p>
<p>If <em>N</em> is not zero, then the attributes will be updated every <em>N</em>
steps.</p>
<div class="admonition warning">
<p class="first admonition-title">Warning</p>
<p class="last">Actually, only atom attributes specified by keywords
like <em>xu</em> or <em>vy</em> are initially stored immediately at the point in
your input script when the fix is defined. Attributes specified by a
compute, fix, or variable are not initially stored until the first run
following the fix definition begins. This is because calculating
those attributes may require quantities that are not defined in
between runs.</p>
</div>
<p>The list of possible attributes is the same as that used by the <a class="reference internal" href="dump.html"><em>dump custom</em></a> command, which describes their meaning.</p>
<p>If the <em>com</em> keyword is set to <em>yes</em> then the <em>xu</em>, <em>yu</em>, and <em>zu</em>
inputs store the position of each atom relative to the center-of-mass
of the group of atoms, instead of storing the absolute position. This
option is used by the <a class="reference internal" href="compute_msd.html"><em>compute msd</em></a> command.</p>
<p>The requested values are stored in a per-atom vector or array as
discussed below. Zeroes are stored for atoms not in the specified
group.</p>
</div>
<div class="section" id="restart-fix-modify-output-run-start-stop-minimize-info">
<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>
<p>This fix writes the per-atom values it stores to <a class="reference internal" href="restart.html"><em>binary restart files</em></a>, so that the values can be restored when a
simulation is restarted. See the <a class="reference internal" href="read_restart.html"><em>read_restart</em></a>
command for info on how to re-specify a fix in an input script that
reads a restart file, so that the operation of the fix continues in an
uninterrupted fashion.</p>
<p>None of the <a class="reference internal" href="fix_modify.html"><em>fix_modify</em></a> options are relevant to this
fix.</p>
<p>If a single input is specified, this fix produces a per-atom vector.
If multiple inputs are specified, a per-atom array is produced where
the number of columns for each atom is the number of inputs. These
can be accessed by various <a class="reference internal" href="Section_howto.html#howto-15"><span>output commands</span></a>. The per-atom values be
accessed on any timestep.</p>
<p>No parameter of this fix can be used with the <em>start/stop</em> keywords of
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>
</div>
<div class="section" id="restrictions">
<h2>Restrictions<a class="headerlink" href="#restrictions" title="Permalink to this headline"></a></h2>
<blockquote>
<div>none</div></blockquote>
</div>
<div class="section" id="related-commands">
<h2>Related commands<a class="headerlink" href="#related-commands" title="Permalink to this headline"></a></h2>
<p><a class="reference internal" href="dump.html"><em>dump custom</em></a>, <a class="reference internal" href="compute_property_atom.html"><em>compute property/atom</em></a>,
<a class="reference internal" href="fix_property_atom.html"><em>fix property/atom</em></a>, <a class="reference internal" href="variable.html"><em>variable</em></a></p>
</div>
<div class="section" id="default">
<h2>Default<a class="headerlink" href="#default" title="Permalink to this headline"></a></h2>
<p>The option default is com = no.</p>
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