Although the true structure of La₂CuO₄ is orthorhombic, it can be approximated as tetragonal with space group #139 I4/mmm, unit-cell parameters of a = 3.814 Å and c = 13.15 Å, and crystallo graphically non-equivalent atoms at the following coordinates (and Wyckoff sites): Cu 0 0 0 (2a); La 0 0 0.362 (4e); O1 0 ½ 0 (4c); O2 0 0 0.187 (4e). The symmetry generates equivalent positions: Rotational symmetry generates the additional coordinate ½ 0 0 for Wyckoff site 4c and 0 0 −z for Wyckoff site 4e. Translational symmetry generates equivalent positions at (½,½,½)+ for all coordinates of the four Wyckoff sites.

(a) Sketch the structure.

(b) State the coordination geometry around each metal ion.

(c) Calculate the Cu–O bond distances.