[Mattia]

1) What is the lattice defined by the sulfur atoms in the tetragonal structure of Cooperite? I imagine that the platinum atoms are arranged at the vertices of a tetrahedron. What is the distance of Pt-S bond and the bond angles around the platinum? I think the bond angles are those of the tetrahedral structure (109.47 °), but I'm not sure. I know that the distance between two atoms of sulfur along the side of the base is 4.91 Å and the distance between two sulfur atoms along the vertical edge is 3.05 Å.

2) What lattices define the cations (black spheres) in the three species with the cell volume doubles? (See Figure 1 of the following file: http://www.chimdocet.it/SITO_ESERCIZI/Esercizi/Comp2_2007.pdf). I think that the two structures at the top have packing ccb, but I'm not sure.