DFT-guided Lennard-Jones parametrization for accurate CO 2 , N 2 , and CH 4 adsorption in MoOFOUR-1-Ni

Area of Science:

• Materials Science
• Computational Chemistry
• Separation Science

Background:

• Anion-pillared metal-organic frameworks (APMOFs) show promise for natural gas purification due to strong electrostatic interactions.
• Classical force fields struggle to accurately model the localized polarization effects in APMOFs, limiting their predictive power.

Purpose of the Study:

• To develop a system-specific force field for the [MoO4]2- pillar in the MoOFOUR-1-Ni APMOF.
• To improve the accuracy of molecular simulations for gas adsorption in APMOFs, specifically for CO2, N2, and CH4.

Main Methods:

• A DFT-guided workflow was used to parameterize Lennard-Jones potentials for the [MoO4]2- anion.
• Density Functional Theory (DFT) calculations determined interaction energies and partial charges.
• Grand Canonical Monte Carlo (GCMC) simulations were performed using the optimized force field, validated against experimental adsorption data.

Main Results:

• The developed force field significantly reduced the mean absolute error for CO2 adsorption by five-fold compared to generic force fields (UFF+DREIDING).
• Excellent agreement was achieved for N2 and CH4 adsorption, validating the model's performance.
• The study highlights the substrate-specific nature of the derived parameters.

Conclusions:

• A DFT-guided approach successfully created a system-specific force field for APMOFs, enhancing simulation accuracy.
• This work demonstrates the limitations of transferable force fields in complex ionic environments and provides a more reliable tool for APMOF research.