wyckoffs:
- "a"
- "a"
- "b"
- "b"
- "d"
- "d"
- "d"
- "d"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"
- "k"