This model contains three variables: TO length, TOT and OTO angles. Within the zeolite model of gis-ZIF-1, the asymmetric units are TO2 with one type of T center and two types of O bridges, corresponding to the T4O4 for 4MR and TnOn for helical chains. We proceeded to track the distances between TO4 tetrahedra, termed as TT lengths, finding that there are two types of symmetrically identical TT lengths, which vary depending on the type of O bridges involved.