<spanid="index-0"></span><h1>compute ackland/atom command<aclass="headerlink"href="#compute-ackland-atom-command"title="Permalink to this headline">¶</a></h1>
<divclass="section"id="syntax">
<h2>Syntax<aclass="headerlink"href="#syntax"title="Permalink to this headline">¶</a></h2>
<divclass="highlight-python"><divclass="highlight"><pre>compute ID group-ID ackland/atom
</pre></div>
</div>
<ulclass="simple">
<li>ID, group-ID are documented in <aclass="reference internal"href="compute.html"><em>compute</em></a> command</li>
<li>ackland/atom = style name of this compute command</li>
</ul>
</div>
<divclass="section"id="examples">
<h2>Examples<aclass="headerlink"href="#examples"title="Permalink to this headline">¶</a></h2>
<divclass="highlight-python"><divclass="highlight"><pre>compute 1 all ackland/atom
</pre></div>
</div>
</div>
<divclass="section"id="description">
<h2>Description<aclass="headerlink"href="#description"title="Permalink to this headline">¶</a></h2>
<p>Defines a computation that calculates the local lattice structure
according to the formulation given in <aclass="reference internal"href="#ackland"><span>(Ackland)</span></a>.</p>
<p>In contrast to the <aclass="reference internal"href="compute_centro_atom.html"><em>centro-symmetry parameter</em></a> this method is stable against
temperature boost, because it is based not on the distance between
particles but the angles. Therefore statistical fluctuations are
averaged out a little more. A comparison with the Common Neighbor
Analysis metric is made in the paper.</p>
<p>The result is a number which is mapped to the following different
lattice structures:</p>
<ulclass="simple">
<li>0 = UNKNOWN</li>
<li>1 = BCC</li>
<li>2 = FCC</li>
<li>3 = HCP</li>
<li>4 = ICO</li>
</ul>
<p>The neighbor list needed to compute this quantity is constructed each
time the calculation is performed (i.e. each time a snapshot of atoms
is dumped). Thus it can be inefficient to compute/dump this quantity
too frequently or to have multiple compute/dump commands, each of
which computes this quantity.-</p>
<p><strong>Output info:</strong></p>
<p>This compute calculates a per-atom vector, which can be accessed by
any command that uses per-atom values from a compute as input. See
<aclass="reference internal"href="Section_howto.html#howto-15"><span>Section_howto 15</span></a> for an overview of
LAMMPS output options.</p>
</div>
<divclass="section"id="restrictions">
<h2>Restrictions<aclass="headerlink"href="#restrictions"title="Permalink to this headline">¶</a></h2>
<p>This compute is part of the USER-MISC package. It is only enabled if
LAMMPS was built with that package. See the <aclass="reference internal"href="Section_start.html#start-3"><span>Making LAMMPS</span></a> section for more info.</p>
<p>The per-atom vector values will be unitless since they are the
integers defined above.</p>
</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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