Define here the cell position.
Translation
The origin of a cell object, defined by its (0 0 0) node,
can be set using the
x,
y,
z entries.
By default, in
Conventional,
Primitive and
Parallelepiped volumes, this node is at a corner
of the cell volume, in a
Sphere volume it is at the
center, and in a
Wigner volume it is at the center of
the first Wigner-Seitz cell.
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.
To define exactly the cell translation, relatively to other cell
or relatively to the current layer, press
Align.
Rotation
The orientation of a cell object, defined by the Euler angles theta,
phi, psi, can be set using the
E1,
E2,
E3 entries.
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.
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).
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.
To define exactly the cell rotation, relatively to other cell
or relatively to the current layer, press
Align.