Set here the polygon representation and atomic structure for a single plane.
To modify a plane, click over its graphic image, or write its identification
(name and number) on the
Plane entry. To modify a list of planes, press
the button
List (after creating the list of planes with
Plane->Select).
Parameters for empty entries or
Local choices remain unchanged.
To change a plane name write the new name in the
Plane entry,
followed by the plane number (GAMGI needs the number to identify the plane).
To change the name for a list of planes, press
List first
and then write the new common name in the
Name entry.
Structure
It is often useful to recreate in a plane the atomic
structure existing in the parent object. A list is first
created, with all the atoms closer to the plane than
the distance defined by
Thickness.
When
Structure is set to
Copy, listed atoms
are copied to the atomic or crystallographic plane just created.
When
Structure is set to
Link, listed atoms
are linked to the atomic or crystallographic plane just created.
When
Structure is set to
None, only a polygonal
representation of the plane is created, without atoms.
Filter
After collecting a list of atoms close enough to the plane,
a filtering condition may be applied. This can be very useful
to avoid atom superposition, resulting for example from atoms
copied before to different planes.
When
Filter is set to
Class,
atoms belonging to another planes are ignored.
When
Filter is set to
Child, atoms not
belonging directly to the plane parent are ignored.
When
Filter is set to
Identical, atoms
closer than a given distance (currently
1.0E-2,
as defined in
GAMGI_MATH_TOLERANCE_STRUCTURE) to
a previous atom are ignored.
When
Filter is set to
None, no filtering
condition is applied.
Thickness
The polygonal representation of the plane is expanded as much as
possible, limited by the cell volume, in crystallographic planes,
and by the atoms within a
Thickness range of the plane
defined by the three atoms, in atomic planes.
Range
A crystallographic plane does not exist as a single plane, is always
part of a family of infinite planes, passing through all the lattice
nodes, with equal distances between them. Each plane of a family
(h k l) intersects the lattice in n/h n/k n/l, where n = 0 means
the plane passing through the origin and n = 1 is the usual
representation of the plane closest to the origin.
The range of planes to create is defined by the values entered near to
the buttons
Start and
End, describing the initial and final
values of n. For example, setting
Start to
-1 and
End
to
1 creates 3 planes, intersecting the axes in: 1) -1/h -1/k -1/l;
2) 0; 3) 1/h 1/k 1/l. By default, only the nearest plane to the origin is
considered:
Start =
1 and
End =
1.
Pressing the
Start button, the entry is disabled and GAMGI creates
automatically all the planes from the beginning of the cell volume to the
final plane specified. Pressing the
End button, the entry is disabled
and GAMGI creates automatically all the planes from the end of the cell volume
to the first plane specified. When both buttons are pressed, GAMGI creates
automatically all the planes from the beginning to the end of the cell volume.
Node
A plane can also be defined indicating explicitly the coordinates of
a node where the plane passes. For each plane family, there is a plane
passing through the origin node and as nodes are equivalent, it follows
that for any node, there is a plane of any family passing through there.
To select the node, press
Node, to open a second level dialog.
O1, O2, O3
These entries provide the coordinates of the node in the lower-left
corner of the cell where the plane passes, calculated with conventional
or primitive cell vectors. When the lattice is primitive or vectors are
primitive, this corner node becomes the place where the plane passes.
O4
When the lattice is centered and vectors are conventional, a fourth
coordinate
O4 is needed to point the centered node where the
plane passes. By default,
o4 is
000, so no change is
introduced. When the cell lattice is primitive
P or the vectors
defining the node are primitive, that is the only possible value for
o4. For I, C, F, R centered lattices,
o4 can also take
the values:
I: 111
C: 110
F: 110, 101, 011
R: 211, 122
corresponding to the numerators of the inner node coordinates,
(1/2 1/2 1/2) for
I lattices, (1/2 1/2 0) for
C
lattices, (0 1/2 1/2) (1/2 0 1/2) (1/2 1/2 0) for
F
lattices and (1/3 2/3 2/3) (2/3 1/3 1/3) for
R lattices.
After entering the node coordinates, pressing
Ok saves the data,
closes the second level dialog, and disables the range information in
the first level dialog. Pressing
Cancel, the current data in
both dialogs is maintained and the second level dialog is closed.
Pressing
Range in the first level dialog, removes the second
level data, closes the second level dialog, enables and initializes
(if empty) the range data.
The vectors used for the node coordinates,
Conventional
or
Primitive, are those used to define the plane indices,
in the
Type page, of the first dialog.
When adding information in the second level dialog, the cell must
have been entered before, so GAMGI can check if the node information is
correct or not. For the same reason, when the
Cell or
Vectors
information in the
Type page is changed, all the information in the
second level dialog is automatically discarded, as it might be wrong.