By allowing exaggerated deformation of the framework, the underconstrained Zn-imidazolate interactions described above impacts the bulk properties of the ReaxFF glass. We report from our simulations a density of 1.68 g cm , significantly larger than the crystal density of 1.21 g cm -3 . Comparison with the ab initio glass is not possible as they were generated using a constant-volume (N, V, T ) ensemble, which does not capture changes in density. Direct experimental comparison of these densities computed from the atomic structure is limited: they correspond to crystallographic densities, while almost all densities measurements performed for glasses utilized pycnometry . Nevertheless, pycnometric densities of 1.63 g cm -3