ACS Spring 2023

CRAFTED - An exploratory database of simulated adsorption isotherms of metal-organic frameworks

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Grand Canonical Monte Carlo is one of the most used methods for simulating the adsorption of gases in nanoporous solids such as metal-organic frameworks (MOF), covalent organic frameworks (COF), zinc-imidazole frameworks (ZIF), and zeolites. In these simulations, the framework is often kept rigid with the framework-adsorbate interactions modeled using a classical force field, where the van der Waals energy is calculated using the Lennard-Jones potential with parameters, and the electrostatics using partial atomic charges. The choice of force field parameters and partial charge assignment schemes can have a major impact on the simulation results. Nevertheless, there are very few databases available to support a comprehensive evaluation of this impact. Here we present a database of simulated adsorption isotherms on 726 MOF structures taken from the CoRE MOF 2014 database. The simulations were performed for the adsorption of CO2 and N2 with two force fields (UFF and DREIDING), four partial charge schemes (no charge, Qeq, EQeq, and DDEC), at three temperatures (273, 298, 323 K) within pressures ranging from 0.001 to 1 bar for N2, and from 0.001 to 10 bar for CO2. The resulting data composes the Charge-dependent, Reproducible, Accessible, Forcefield-dependent, and Temperature-dependent Exploratory Database (CRAFTED) of adsorption isotherms. Figure 1 presents an example of the diversity of results that can arise from such combinations of parameters. The CRAFTED database is freely available on Zenodo (#7106174) and provides 34,848 adsorption isotherms with their respective enthalpy of adsorption, the charge-assigned CIF files, force field and molecule definition files, RASPA input files, and an interactive visualization interface. This database builds a powerful platform to explore the sensitivity of simulation outcomes to molecular modeling choices at the material (structure-property relationship) and process levels (structure-property-performance relationship).