reference
When
reference is
cell, the direction is crystallographic
so direction indices are required and its parent must be a cell.
When
reference is
atoms, the direction is described
by two xyz coordinates so the direction becomes independent of the
atoms used to define it.
Example: <direction ... reference="cell"/> (default)
Allowed values: cell, atoms (optional)
u, v, w
Set the indices
u, v, w defining a crystallographic direction.
The three indices cannot be all zero. An error is shown when these
indices are not indicated for a crystallographic direction or when
they are indicated for an atomic direction.
Example: <direction ... u="1" v="0" w="0"/> (no default)
Allowed values: integer (required, coupled)
vectors
Set the type of cell vectors,
conventional or
primitive,
used to determine the direction with
u,
v,
w indices.
When the lattice is primitive there is no difference between
conventional or
primitive cell vectors.
An error is shown when
vectors is set for an atomic direction.
Example: <direction ... vectors="conventional"/> (default)
(defined in GAMGI_PHYS_DIRECTION_VECTORS)
Allowed values: conventional, primitive (optional)
model
An atomic direction is always represented as a
line.
A crystallographic direction can also be represented as a
pole or a
trace (for projected directions).
Example: <direction ... model="line"/> (default)
Allowed values: line, pole, trace (optional)