autonomy
When
autonomy is
none, rotating, moving, scaling the
direction corresponds to rotating, moving, scaling the parent object. For
crystallographic directions, the parent object is the cell containing the
relevant crystallographic information. Atoms in the
thickness
region are linked to atomic directions.
When
autonomy is
all or
partial, the crystallographic
or atomic direction can be rotated, moved, scaled, independently of its parent.
When
autonomy is
partial, atoms in the
thickness
region were linked to the atomic or crystallographic direction.
When
autonomy is
all, atoms in the
thickness
region were copied to the atomic or crystallographic direction.
Example: <direction ... autonomy="none"/> (default)
Allowed values: all, partial, none (optional)
thickness
The polygonal representation of the direction is expanded as much as
possible, limited by the cell volume, in crystallographic directions,
and by the atoms within the
thickness range of the direction
defined by the first two atoms, in atomic directions.
Example: <direction ... thickness="0.0100"/> (default)
(defined in GAMGI_CHEM_DIRECTION_THICKNESS)
Allowed values: positive real (optional)
o1, o2, o3
A direction can be defined indicating explicitly the coordinates of a node
where the direction passes. For each direction family, there is a direction
passing through the origin node and as nodes are equivalent, it follows
that for any node, there is a direction of any family passing through there.
When the lattice is primitive or vectors are primitive, coordinates
o1,
o2,
o3 are enough to identify any cell node.
By default, a crystallographic direction passes through the origin,
with node coordinates equal to
0,
0,
0, respectively.
Example: <direction ... o1="0" o2="0" o3="0"/> (default)
Allowed values: integer (optional, coupled)
o4
When the lattice is centered and vectors are conventional, the coordinates
o1,
o2,
o3 indicate the node in the lower-left
corner of the cell where the direction passes. A fourth coordinate
o4
is needed to point the centered node where the direction 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.
Example: <direction ... o4="000"/> (default)
Allowed values: 000, 111, 110 101, 011, 211, 122 (optional)