<p>Coefficients parameterized by <a class="reference internal" href="#peng"><span class="std std-ref">(Peng)</span></a> are assigned for each
atom type designating the chemical symbol and charge of each atom
type. Valid chemical symbols for compute xrd are:</p>
<table border="1" class="docutils">
<colgroup>
<col width="19%" />
<col width="19%" />
<col width="19%" />
<col width="23%" />
<col width="19%" />
</colgroup>
<tbody valign="top">
<tr class="row-odd"><td>H</td>
<td>He1-</td>
<td>He</td>
<td>Li</td>
<td>Li1+</td>
</tr>
<tr class="row-even"><td>Be</td>
<td>Be2+</td>
<td>B</td>
<td>C</td>
<td>Cval</td>
</tr>
<tr class="row-odd"><td>N</td>
<td>O</td>
<td>O1-</td>
<td>F</td>
<td>F1-</td>
</tr>
<tr class="row-even"><td>Ne</td>
<td>Na</td>
<td>Na1+</td>
<td>Mg</td>
<td>Mg2+</td>
</tr>
<tr class="row-odd"><td>Al</td>
<td>Al3+</td>
<td>Si</td>
<td>Sival</td>
<td>Si4+</td>
</tr>
<tr class="row-even"><td>P</td>
<td>S</td>
<td>Cl</td>
<td>Cl1-</td>
<td>Ar</td>
</tr>
<tr class="row-odd"><td>K</td>
<td>Ca</td>
<td>Ca2+</td>
<td>Sc</td>
<td>Sc3+</td>
</tr>
<tr class="row-even"><td>Ti</td>
<td>Ti2+</td>
<td>Ti3+</td>
<td>Ti4+</td>
<td>V</td>
</tr>
<tr class="row-odd"><td>V2+</td>
<td>V3+</td>
<td>V5+</td>
<td>Cr</td>
<td>Cr2+</td>
</tr>
<tr class="row-even"><td>Cr3+</td>
<td>Mn</td>
<td>Mn2+</td>
<td>Mn3+</td>
<td>Mn4+</td>
</tr>
<tr class="row-odd"><td>Fe</td>
<td>Fe2+</td>
<td>Fe3+</td>
<td>Co</td>
<td>Co2+</td>
</tr>
<tr class="row-even"><td>Co</td>
<td>Ni</td>
<td>Ni2+</td>
<td>Ni3+</td>
<td>Cu</td>
</tr>
<tr class="row-odd"><td>Cu1+</td>
<td>Cu2+</td>
<td>Zn</td>
<td>Zn2+</td>
<td>Ga</td>
</tr>
<tr class="row-even"><td>Ga3+</td>
<td>Ge</td>
<td>Ge4+</td>
<td>As</td>
<td>Se</td>
</tr>
<tr class="row-odd"><td>Br</td>
<td>Br1-</td>
<td>Kr</td>
<td>Rb</td>
<td>Rb1+</td>
</tr>
<tr class="row-even"><td>Sr</td>
<td>Sr2+</td>
<td>Y</td>
<td>Y3+</td>
<td>Zr</td>
</tr>
<tr class="row-odd"><td>Zr4+</td>
<td>Nb</td>
<td>Nb3+</td>
<td>Nb5+</td>
<td>Mo</td>
</tr>
<tr class="row-even"><td>Mo3+</td>
<td>Mo5+</td>
<td>Mo6+</td>
<td>Tc</td>
<td>Ru</td>
</tr>
<tr class="row-odd"><td>Ru3+</td>
<td>Ru4+</td>
<td>Rh</td>
<td>Rh3+</td>
<td>Rh4+</td>
</tr>
<tr class="row-even"><td>Pd</td>
<td>Pd2+</td>
<td>Pd4+</td>
<td>Ag</td>
<td>Ag1+</td>
</tr>
<tr class="row-odd"><td>Ag2+</td>
<td>Cd</td>
<td>Cd2+</td>
<td>In</td>
<td>In3+</td>
</tr>
<tr class="row-even"><td>Sn</td>
<td>Sn2+</td>
<td>Sn4+</td>
<td>Sb</td>
<td>Sb3+</td>
</tr>
<tr class="row-odd"><td>Sb5+</td>
<td>Te</td>
<td>I</td>
<td>I1-</td>
<td>Xe</td>
</tr>
<tr class="row-even"><td>Cs</td>
<td>Cs1+</td>
<td>Ba</td>
<td>Ba2+</td>
<td>La</td>
</tr>
<tr class="row-odd"><td>La3+</td>
<td>Ce</td>
<td>Ce3+</td>
<td>Ce4+</td>
<td>Pr</td>
</tr>
<tr class="row-even"><td>Pr3+</td>
<td>Pr4+</td>
<td>Nd</td>
<td>Nd3+</td>
<td>Pm</td>
</tr>
<tr class="row-odd"><td>Pm3+</td>
<td>Sm</td>
<td>Sm3+</td>
<td>Eu</td>
<td>Eu2+</td>
</tr>
<tr class="row-even"><td>Eu3+</td>
<td>Gd</td>
<td>Gd3+</td>
<td>Tb</td>
<td>Tb3+</td>
</tr>
<tr class="row-odd"><td>Dy</td>
<td>Dy3+</td>
<td>Ho</td>
<td>Ho3+</td>
<td>Er</td>
</tr>
<tr class="row-even"><td>Er3+</td>
<td>Tm</td>
<td>Tm3+</td>
<td>Yb</td>
<td>Yb2+</td>
</tr>
<tr class="row-odd"><td>Yb3+</td>
<td>Lu</td>
<td>Lu3+</td>
<td>Hf</td>
<td>Hf4+</td>
</tr>
<tr class="row-even"><td>Ta</td>
<td>Ta5+</td>
<td>W</td>
<td>W6+</td>
<td>Re</td>
</tr>
<tr class="row-odd"><td>Os</td>
<td>Os4+</td>
<td>Ir</td>
<td>Ir3+</td>
<td>Ir4+</td>
</tr>
<tr class="row-even"><td>Pt</td>
<td>Pt2+</td>
<td>Pt4+</td>
<td>Au</td>
<td>Au1+</td>
</tr>
<tr class="row-odd"><td>Au3+</td>
<td>Hg</td>
<td>Hg1+</td>
<td>Hg2+</td>
<td>Tl</td>
</tr>
<tr class="row-even"><td>Tl1+</td>
<td>Tl3+</td>
<td>Pb</td>
<td>Pb2+</td>
<td>Pb4+</td>
</tr>
<tr class="row-odd"><td>Bi</td>
<td>Bi3+</td>
<td>Bi5+</td>
<td>Po</td>
<td>At</td>
</tr>
<tr class="row-even"><td>Rn</td>
<td>Fr</td>
<td>Ra</td>
<td>Ra2+</td>
<td>Ac</td>
</tr>
<tr class="row-odd"><td>Ac3+</td>
<td>Th</td>
<td>Th4+</td>
<td>Pa</td>
<td>U</td>
</tr>
<tr class="row-even"><td>U3+</td>
<td>U4+</td>
<td>U6+</td>
<td>Np</td>
<td>Np3+</td>
</tr>
<tr class="row-odd"><td>Np4+</td>
<td>Np6+</td>
<td>Pu</td>
<td>Pu3+</td>
<td>Pu4+</td>
</tr>
<tr class="row-even"><td>Pu6+</td>
<td>Am</td>
<td>Cm</td>
<td>Bk</td>
<td>Cf</td>
</tr>
</tbody>
</table>
<p>If the <em>echo</em> keyword is specified, compute xrd will provide extra
reporting information to the screen.</p>
<p><strong>Output info:</strong></p>
<p>This compute calculates a global array. The number of rows in the
array is the number of reciprocal lattice nodes that are explored
which by the mesh. The global array has 2 columns.</p>
<p>The first column contains the diffraction angle in the units (radians
or degrees) provided with the <em>2Theta</em> values. The second column contains
the computed diffraction intensities as described above.</p>
<p>The array can be accessed by any command that uses global values from
a compute as input. See <a class="reference internal" href="Section_howto.html#howto-15"><span class="std std-ref">this section</span></a>
for an overview of LAMMPS output options.</p>
<p>All array values calculated by this compute are “intensive”.</p>
</div>
<div class="section" id="restrictions">
<h2>Restrictions</h2>
<p>This compute is part of the USER-DIFFRACTION package. It is only
enabled if LAMMPS was built with that package. See the <a class="reference internal" href="Section_start.html#start-3"><span class="std std-ref">Making LAMMPS</span></a> section for more info.</p>
<p>The compute_xrd command does not work for triclinic cells.</p>
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