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<title>GAMGI Interfaces: Cell Create</title>
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<h1>Cell Create</h1>
<div id="notebook">
<ul>
<li><a href="create_symmetry.html">Symmetry</a></li>
<li><a href="create_volume.html">Volume</a></li>
<li><span>Position</span></li>
<li><a href="create_origin.html">Origin</a></li>
<li><a href="create_view.html">View</a></li>
</ul>
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<div class="contents">
Define here the cell position.
<h3>Translation</h3>
The origin of a cell object, defined by its (0 0 0) node,
can be set using the <b>x</b>, <b>y</b>, <b>z</b> entries.
<p/>
By default, in <b>Conventional</b>, <b>Primitive</b> and
<b>Parallelepiped</b> volumes, this node is at a corner
of the cell volume, in a <b>Sphere</b> volume it is at the
center, and in a <b>Wigner</b> volume it is at the center of
the first Wigner-Seitz cell.
<p/>
A simpler way to set directly the cell position is to click on
the screen, at the wished position, after defining all the other
cell properties: a new cell object is created at that position.
<p/>
To define exactly the cell translation, relatively to other cell
or relatively to the current layer, press <a href="translation.html">
Align</a>.
<h3>Rotation</h3>
The orientation of a cell object, defined by the Euler angles theta,
phi, psi, can be set using the <b>E1</b>, <b>E2</b>, <b>E3</b> entries.
<p/>
Euler angles in GAMGI are defined as follows: first, the (x, y, z)
referential is rotated theta degrees (between 0 and 180) around the
y axis, then the referential is rotated phi degrees (between 0 and 360)
around the initial z axis, and finally it is rotated psi degrees (between
0 and 360) around the new z axis, always in the direct, counter-clockwise,
direction. If the first Euler angle (theta) is zero, the old and new z axis
coincide, thus (0, 0, 10) and (0, 5, 5) represent the same rotation.
<p/>
By default, the first conventional vector is aligned with the x axis
(even if conventional vectors are not actually represented), the second
vector is in the xy plane and the third vector has a positive z coordinate
(pointing to the user), corresponding to Euler angles (0, 0, 0).
<p/>
The cell orientation is independent of the volume representation.
This way, conventional, primitive and Wigner-Seitz cells can be easily
compared, as they have the same orientation.
<p/>
To define exactly the cell rotation, relatively to other cell
or relatively to the current layer, press <a href="rotation.html">
Align</a>.
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