GlidePlanes
Glide planes are symmetry elements in crystallography that combine reflection in a plane with a fractional translation parallel to that plane. After reflecting a point across the plane, the operation translates the result by a portion of a lattice vector lying in the plane. The translation is commonly a half-lattice vector, and the combined operation is distinct from a pure mirror reflection.
Common types of glide planes are described by letters that indicate the direction of the translational component:
- a-glide: translation by half along the a-axis within the plane of reflection
- b-glide: translation by half along the b-axis
- c-glide: translation by half along the c-axis
- n-glide: translation by half along two in-plane directions, typically represented as a diagonal component (for example,
Glide planes are one of the key symmetry elements used to describe the complete symmetry of a
Consequences in crystallography include constraints on atomic positions and systematic absences in X-ray and neutron diffraction,
In practice, glide planes are represented in crystallographic notation and discussed within the frameworks of Schoenflies