Data-driven matching of experimental crystal structures and gas adsorption isotherms of metal-organic frameworks

Abstract

Porous metal-organic frameworks are a class of materials with great promise in gas separation and gas storage applications. Due to the large material space, computational screening techniques have long been an important part of the scientific toolbox. However, a broad validation of molecular simulations in these materials is hampered by the lack of a connection between databases of gas adsorption experiments and databases of the atomic crystal structure of corresponding materials. This work aims to connect the gas adsorption isotherms of metal-organic frameworks collected in the NIST/ARPA-E Database of Novel and Emerging Adsorbent Materials to a corresponding crystal structure in the Cambridge Structural Database. With tens of thousands of isotherms and crystal structures reported to date, an automatic approach is needed to establish this link, which we describe in this paper. As a first application and consistency check, we compare the pore volume deduced from low-temperature argon or nitrogen isotherms to the geometrical pore volume computed from the crystal structure. Overall, 545 argon or nitrogen isotherms could be matched to a corresponding crystal structure. We find that the pore volume computed via the two complementary methods shows acceptable agreement only in about 35% of these cases. We provide the subset of isotherms measured on these materials as a seed for a future, more complete reference data set for computational studies.

Inverse design of metal–organic frameworks for direct air capture of CO2via deep reinforcement learning

“…63,64 The number of MOF structures generated via reinforcement learning was much less than the number used for pre-training, and these were optimized using the Universal Forceeld (UFF) 61 as implemented in the Forcite Module of Materials Studio 2019. 65 The EQEq (extended charge equilibration) method 66,67 was used to generate the partial charges of the framework atoms of the MOFs. The lowest common oxidation states of the elements were chosen as their charge centers.…”