Basic Maths for Protein Crystallographers | |

Atom notation |

An atom in a crystal can be referenced as follows:

- as (x
_{i}) - as a "coordinate triple": x
_{i},y_{i},z_{i} - in vector notation as
x
_{i}**a**+y_{i}**b**+z_{i}**c**

Its position in another unit cell is
(x_{i}+n_{x})**a** + (y_{i}+n_{y})**b** +
(z_{i}+n_{z})**c**.
The atom's position is given **relative to some origin**, which is conveniently chosen
relative to the symmetry axes.