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<li class="toctree-l1"><a class="reference internal" href="Section_intro.html">1. Introduction</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_start.html">2. Getting Started</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_commands.html">3. Commands</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_accelerate.html">5. Accelerating LAMMPS performance</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_howto.html">6. How-to discussions</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_python.html">11. Python interface to LAMMPS</a></li>
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<li>compute property/atom command</li>
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<div class="section" id="compute-property-atom-command">
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<span id="index-0"></span><h1>compute property/atom command<a class="headerlink" href="#compute-property-atom-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>compute ID group-ID property/atom input1 input2 ...
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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="compute.html"><em>compute</em></a> command</li>
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<li>property/atom = style name of this compute command</li>
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<li>input = one or more atom attributes</li>
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</ul>
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<div class="highlight-python"><div class="highlight"><pre>possible attributes = id, mol, proc, type, mass,
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x, y, z, xs, ys, zs, xu, yu, zu, ix, iy, iz,
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vx, vy, vz, fx, fy, fz,
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q, mux, muy, muz, mu,
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radius, diameter, omegax, omegay, omegaz,
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angmomx, angmomy, angmomz,
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shapex,shapey, shapez,
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quatw, quati, quatj, quatk, tqx, tqy, tqz,
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end1x, end1y, end1z, end2x, end2y, end2z,
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corner1x, corner1y, corner1z,
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corner2x, corner2y, corner2z,
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corner3x, corner3y, corner3z,
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nbonds,
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vfrac, s0,
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spin, eradius, ervel, erforce,
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rho, drho, e, de, cv,
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i_name, d_name
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</pre></div>
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</div>
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<div class="highlight-python"><div class="highlight"><pre>id = atom ID
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mol = molecule ID
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proc = ID of processor that owns atom
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type = atom type
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mass = atom mass
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x,y,z = unscaled atom coordinates
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xs,ys,zs = scaled atom coordinates
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xu,yu,zu = unwrapped atom coordinates
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ix,iy,iz = box image that the atom is in
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vx,vy,vz = atom velocities
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fx,fy,fz = forces on atoms
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q = atom charge
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mux,muy,muz = orientation of dipole moment of atom
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mu = magnitude of dipole moment of atom
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radius,diameter = radius,diameter of spherical particle
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omegax,omegay,omegaz = angular velocity of spherical particle
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angmomx,angmomy,angmomz = angular momentum of aspherical particle
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shapex,shapey,shapez = 3 diameters of aspherical particle
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quatw,quati,quatj,quatk = quaternion components for aspherical or body particles
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tqx,tqy,tqz = torque on finite-size particles
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end12x, end12y, end12z = end points of line segment
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corner123x, corner123y, corner123z = corner points of triangle
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nbonds = number of bonds assigned to an atom
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</pre></div>
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</div>
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<div class="highlight-python"><div class="highlight"><pre>PERI package per-atom properties:
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vfrac = ???
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s0 = ???
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</pre></div>
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</div>
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<div class="highlight-python"><div class="highlight"><pre>USER-EFF and USER-AWPMD package per-atom properties:
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spin = electron spin
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eradius = electron radius
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ervel = electron radial velocity
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erforce = electron radial force
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</pre></div>
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</div>
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<div class="highlight-python"><div class="highlight"><pre>USER-SPH package per-atom properties:
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rho = ???
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drho = ???
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e = ???
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de = ???
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cv = ???
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</pre></div>
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</div>
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<pre class="literal-block">
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<a class="reference internal" href="fix_property_atom.html"><em>fix property/atom</em></a> per-atom properties:
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i_name = custom integer vector with name
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d_name = custom integer vector with name
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</pre>
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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>compute 1 all property/atom xs vx fx mux
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compute 2 all property/atom type
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compute 1 all property/atom ix iy iz
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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>Define a computation that simply stores atom attributes for each atom
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in the group. This is useful so that the values can be used by other
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<a class="reference internal" href="Section_howto.html#howto-15"><span>output commands</span></a> that take computes as
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inputs. See for example, the <a class="reference internal" href="compute_reduce.html"><em>compute reduce</em></a>,
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<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>,
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<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>
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<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, with some
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additional quantities that are only defined for certain <a class="reference internal" href="atom_style.html"><em>atom styles</em></a>. Basically, this augmented list gives an
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input script access to any per-atom quantity stored by LAMMPS.</p>
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<p>The values are stored in a per-atom vector or array as discussed
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below. Zeroes are stored for atoms not in the specified group or for
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quantities that are not defined for a particular particle in the group
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(e.g. <em>shapex</em> if the particle is not an ellipsoid).</p>
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<p>The additional quantities only accessible via this command, and not
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directly via the <a class="reference internal" href="dump.html"><em>dump custom</em></a> command, are as follows.</p>
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<p><em>Shapex</em>, <em>shapey</em>, and <em>shapez</em> are defined for ellipsoidal particles
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and define the 3d shape of each particle.</p>
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<p><em>Quatw</em>, <em>quati</em>, <em>quatj</em>, and <em>quatk</em> are defined for ellipsoidal
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particles and body particles and store the 4-vector quaternion
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representing the orientation of each particle. See the <a class="reference internal" href="set.html"><em>set</em></a>
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command for an explanation of the quaternion vector.</p>
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<p><em>End1x</em>, <em>end1y</em>, <em>end1z</em>, <em>end2x</em>, <em>end2y</em>, <em>end2z</em>, are defined for
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line segment particles and define the end points of each line segment.</p>
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<p><em>Corner1x</em>, <em>corner1y</em>, <em>corner1z</em>, <em>corner2x</em>, <em>corner2y</em>,
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<em>corner2z</em>, <em>corner3x</em>, <em>corner3y</em>, <em>corner3z</em>, are defined for
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triangular particles and define the corner points of each triangle.</p>
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<p><em>Nbonds</em> is available for all molecular atom styles and refers to the
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number of explicit bonds assigned to an atom. Note that if the
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<a class="reference internal" href="newton.html"><em>newton bond</em></a> command is set to <em>on</em>, which is the
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default, then every bond in the system is assigned to only one of the
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two atoms in the bond. Thus a bond between atoms I,J may be tallied
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for either atom I or atom J. If <a class="reference internal" href="newton.html"><em>newton bond off</em></a> is set,
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it will be tallied with both atom I and atom J.</p>
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<p>The <em>i_name</em> and <em>d_name</em> attributes refer to custom integer and
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floating-point properties that have been added to each atom via the
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<a class="reference internal" href="fix_property_atom.html"><em>fix property/atom</em></a> command. When that command
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is used specific names are given to each attribute which are what is
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specified as the “name” portion of <em>i_name</em> or <em>d_name</em>.</p>
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<p><strong>Output info:</strong></p>
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<p>This compute calculates a per-atom vector or per-atom array depending
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on the number of input values. If a single input is specified, a
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per-atom vector is produced. If two or more inputs are specified, a
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per-atom array is produced where the number of columns = the number of
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inputs. The vector or array can be accessed by any command that uses
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per-atom values from a compute as input. See <a class="reference internal" href="Section_howto.html#howto-15"><span>this section</span></a> for an overview of LAMMPS output
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options.</p>
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<p>The vector or array values will be in whatever <a class="reference internal" href="units.html"><em>units</em></a> the
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corresponding attribute is in, e.g. velocity units for vx, charge
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units for q, etc.</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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<blockquote>
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<div>none</div></blockquote>
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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="dump.html"><em>dump custom</em></a>, <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_spatial.html"><em>fix ave/spatial</em></a>,
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<a class="reference internal" href="fix_property_atom.html"><em>fix property/atom</em></a></p>
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<p><strong>Default:</strong> none</p>
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