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_ia+y_ib+z_ic

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.