We employed a parametrization of ReaxFF, a flavor of reactive force fields, developed for ZIF materials, and used the same parameters as in our previous work. ReaxFF simulations were performed using LAMMPS. A timestep δt of 0.25 fs was used in the MD runs and, the temperature (and pressure when applicable) were controlled using a Nosé-Hoover thermostat (and barostat). Temperature and pressure damping parameters T damp and P damp were fixed at 100 fs and 1000 fs respectively. Constant-pressure (N, P, T ) simulations were performed using either an isotropic or a flexible cell, respectively, with the LAMMPS keywords iso and tri. Volumetric deformation in the (N, V, T ) ensemble was a continuous process lasting τ ∆V = 250 ps, during which each dimension of the box changed linearly with time from its initial to final value to achieve a volume reduction by 1.5%. To reduce finite size effects, a (2 × 2 × 2) supercell of ZIF-4 with 2,176 atoms was simulated.