In addition to the above experiments, we have also performed ab initio molecular dynamics (AIMD) simulations of the ZIF-62-bImCl R=0.5 system at 1000 K. The simulated system consisted of a single unit cell of crystalline ZIF-62 (296 atoms) mixed with 8 bImH + and 8 Cl -. After 10 ps of simulation, we find an overall decrease in energy (converged after ~6 ps, see Supplementary Fig. ) and that all 8 Cl -atoms are coordinated to Zn atoms (bond length of ~2.2 Å), with one case of an imidazolate linker obtaining a hydrogen atom from the added benzimidazolium. Based on this simulation, we show the partial PDFs of the most relevant atomic pair-correlations in Fig. . These results were also used in the assignment the experimental peaks in Fig. , confirming that the observed bond lengths correspond very well with newly formed peaks in the ZIF-62-bImCl (R=0.5) glass. Lastly, based on the performed AIMD simulation, we present an example configuration of a Zn node coordinated with a mixture of (benz)imidazolate and chloride (Fig. ). Interestingly, in the AIMD simulation, we observe some cases of Zn-Cl-Zn bridges (like the bonding in crystalline ZnCl2). We hypothesize that these may also be formed experimentally upon evaporation of free or non-bridging (benz)imidazole species (as observed experimentally, see Supporting Text). This explains the observed increase in Tg of the modified ZIF glasses upon subsequent annealing (see Supplementary Fig. and Supplementary Text), since the structure should become more rigid when non-bridging imidazolate linkers are replaced by bridging halide species.