Flexible and Transferable ab Initio Force Field for Zeolitic Imidazolate Frameworks: ZIF-FF

TT Weng and JR Schmidt, JOURNAL OF PHYSICAL CHEMISTRY A, 123, 3000-3012 (2019).

DOI: 10.1021/acs.jpca.8b12311

We have developed a transferable ab initio intramolecular force field for zeolitic imidazolate frameworks (ZIFs), "ZIF-FF", that is capable of quantitatively describing the structural properties and relative stabilities of ZIFs. In contrast to nearly all prior force fields, ZIF- FF properly describes the relative stability of ZIF polymorphs, a crucial element in ZIF nucleation and crystal growth. Beginning with a general Amber force field (GAFF), Zn-related force field parameters were optimized against dispersion-corrected DFTcalculated properties using a genetic algorithm. We validated the resulting force field by examining bond and angle distributions, phonon density of states, mechanical properties, diffusion properties and via modeling a ZIF amorphization process. Furthermore, we find that ZIF-FF is transferable, successfully describing relative stability of various ZIF surface structures, as well as the densities of ZIFs with diverse functionalized linkers.

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