No. 1 p 1

Number

1

Hermann–Mauguin symbol

p 1

Lattice

Oblique

Operations per cell

1

General position

1a (site symmetry 1)

Wyckoff positions (standard setting)

How to read it

• Each symmetry element drawn in the cell is worked out from the group’s operations. This is a two-dimensional group, so there are only rotation points and mirror or glide lines: rotation points are small filled shapes marked with their order (2, 3, 4 or 6), and mirror and glide lines run across the cell (dashed outline = glide). Colours: 2-fold red, 3-fold green, 4-fold blue, 6-fold purple.
• The multiplicity is how many equivalent points an atom on that site generates in the conventional cell; the general position has the highest multiplicity, equal to the number of operations.
• Site symmetry is the point group that leaves that position fixed; a special position (lower multiplicity) sits on a symmetry element — press + on a row to see its atoms land on the drawn elements.