\b[A motif can have fivefold <symmetry>.] For example, repeat an identically oriented regular pentagonal molecular motif at every point of a square translation lattice. Each isolated motif has fivefold <rotational symmetry>, while the <crystal structure> as a whole does not: rotating about one motif fails to map the other motif centres onto <lattice points>. The <symmetry> of an <atomic basis of a crystal> need not be a <symmetry> of its <Bravais lattice>.

Solution

Past exam of the materials science course of the University of Cambridge / 2022 / Paper 1 / 1 / a / ii / Solution

 Solution (source code)