Ring sizes are computed by counting the number of different units (Zn and Im) in each ring; always even, they are equal to twice the T-based ring sizes usually reported for zeolitic nets. These distributions of ring sizes, reported on Figure , show that both glasses have topologies that deviate from the crystal perfectly defined 8, 12 and 16 rings. However, the two glass models display very different topologies, with the ReaxFF glass having a higher proportion of larger rings than the ab initio glass. It demonstrates that it is less ordered at medium range, a result arising from the too weak constraints on the Zn-imidazolate interactions.