Yes, it's called "crystallography", where "crystal" = densest possible packing of identical repeating smaller units (identical => pure). The smaller the molecule the greater symmetry the smaller units have (in general) and therefore the more specific the crystalline structure. (Any variation with T or P is due to the different thermal properties of the constituents, themselves, of each molecule) Some predictions can be made: crystals are classified according to the structure of their lattices, or according to the type of bond that holds them together (i.e. ionic, covalent or metallic), crystals are divided into seven classes (32 sub-classes): cubic, tetragonal, orthorhombic, hexagonal, trigonal, monoclinic, and triclinic, there is a correlation between geometric class and type of bond or lattice. The maths of group theory is also useful. (P.S. solids exist more because of FLT than Q.M.)