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<div class="section" id="compute-property-atom-command">
<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>
<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>compute ID group-ID property/atom input1 input2 ...
</pre></div>
</div>
<ul class="simple">
<li>ID, group-ID are documented in <a class="reference internal" href="compute.html"><em>compute</em></a> command</li>
<li>property/atom = style name of this compute command</li>
<li>input = one or more atom attributes</li>
</ul>
<div class="highlight-python"><div class="highlight"><pre>possible attributes = id, mol, proc, type, mass,
x, y, z, xs, ys, zs, xu, yu, zu, ix, iy, iz,
vx, vy, vz, fx, fy, fz,
q, mux, muy, muz, mu,
radius, diameter, omegax, omegay, omegaz,
angmomx, angmomy, angmomz,
shapex,shapey, shapez,
quatw, quati, quatj, quatk, tqx, tqy, tqz,
end1x, end1y, end1z, end2x, end2y, end2z,
corner1x, corner1y, corner1z,
corner2x, corner2y, corner2z,
corner3x, corner3y, corner3z,
nbonds,
vfrac, s0,
spin, eradius, ervel, erforce,
rho, drho, e, de, cv,
i_name, d_name
</pre></div>
</div>
<div class="highlight-python"><div class="highlight"><pre>id = atom ID
mol = molecule ID
proc = ID of processor that owns atom
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 dipole moment of atom
mu = magnitude of dipole moment of atom
radius,diameter = radius,diameter of spherical particle
omegax,omegay,omegaz = angular velocity of spherical particle
angmomx,angmomy,angmomz = angular momentum of aspherical particle
shapex,shapey,shapez = 3 diameters of aspherical particle
quatw,quati,quatj,quatk = quaternion components for aspherical or body particles
tqx,tqy,tqz = torque on finite-size particles
end12x, end12y, end12z = end points of line segment
corner123x, corner123y, corner123z = corner points of triangle
nbonds = number of bonds assigned to an atom
</pre></div>
</div>
<div class="highlight-python"><div class="highlight"><pre>PERI package per-atom properties:
vfrac = ???
s0 = ???
</pre></div>
</div>
<div class="highlight-python"><div class="highlight"><pre>USER-EFF and USER-AWPMD package per-atom properties:
spin = electron spin
eradius = electron radius
ervel = electron radial velocity
erforce = electron radial force
</pre></div>
</div>
<div class="highlight-python"><div class="highlight"><pre>USER-SPH package per-atom properties:
rho = ???
drho = ???
e = ???
de = ???
cv = ???
</pre></div>
</div>
<pre class="literal-block">
<a class="reference internal" href="fix_property_atom.html"><em>fix property/atom</em></a> per-atom properties:
i_name = custom integer vector with name
d_name = custom integer vector with name
</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>compute 1 all property/atom xs vx fx mux
compute 2 all property/atom type
compute 1 all property/atom ix iy iz
</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 computation that simply stores atom attributes for each atom
in the group. This is useful so that the values can be used by other
<a class="reference internal" href="Section_howto.html#howto-15"><span>output commands</span></a> that take computes as
inputs. 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>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
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
input script access to any per-atom quantity stored by LAMMPS.</p>
<p>The values are stored in a per-atom vector or array as discussed
below. Zeroes are stored for atoms not in the specified group or for
quantities that are not defined for a particular particle in the group
(e.g. <em>shapex</em> if the particle is not an ellipsoid).</p>
<p>The additional quantities only accessible via this command, and not
directly via the <a class="reference internal" href="dump.html"><em>dump custom</em></a> command, are as follows.</p>
<p><em>Shapex</em>, <em>shapey</em>, and <em>shapez</em> are defined for ellipsoidal particles
and define the 3d shape of each particle.</p>
<p><em>Quatw</em>, <em>quati</em>, <em>quatj</em>, and <em>quatk</em> are defined for ellipsoidal
particles and body particles and store the 4-vector quaternion
representing the orientation of each particle. See the <a class="reference internal" href="set.html"><em>set</em></a>
command for an explanation of the quaternion vector.</p>
<p><em>End1x</em>, <em>end1y</em>, <em>end1z</em>, <em>end2x</em>, <em>end2y</em>, <em>end2z</em>, are defined for
line segment particles and define the end points of each line segment.</p>
<p><em>Corner1x</em>, <em>corner1y</em>, <em>corner1z</em>, <em>corner2x</em>, <em>corner2y</em>,
<em>corner2z</em>, <em>corner3x</em>, <em>corner3y</em>, <em>corner3z</em>, are defined for
triangular particles and define the corner points of each triangle.</p>
<p><em>Nbonds</em> is available for all molecular atom styles and refers to the
number of explicit bonds assigned to an atom. Note that if the
<a class="reference internal" href="newton.html"><em>newton bond</em></a> command is set to <em>on</em>, which is the
default, then every bond in the system is assigned to only one of the
two atoms in the bond. Thus a bond between atoms I,J may be tallied
for either atom I or atom J. If <a class="reference internal" href="newton.html"><em>newton bond off</em></a> is set,
it will be tallied with both atom I and atom J.</p>
<p>The <em>i_name</em> and <em>d_name</em> attributes refer to custom integer and
floating-point properties that have been added to each atom via the
<a class="reference internal" href="fix_property_atom.html"><em>fix property/atom</em></a> command. When that command
is used specific names are given to each attribute which are what is
specified as the &#8220;name&#8221; portion of <em>i_name</em> or <em>d_name</em>.</p>
<p><strong>Output info:</strong></p>
<p>This compute calculates a per-atom vector or per-atom array depending
on the number of input values. If a single input is specified, a
per-atom vector is produced. If two or more inputs are specified, a
per-atom array is produced where the number of columns = the number of
inputs. The vector or array can be accessed by any command that uses
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
options.</p>
<p>The vector or array values will be in whatever <a class="reference internal" href="units.html"><em>units</em></a> the
corresponding attribute is in, e.g. velocity units for vx, charge
units for q, etc.</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_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>,
<a class="reference internal" href="fix_property_atom.html"><em>fix property/atom</em></a></p>
<p><strong>Default:</strong> none</p>
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