DFT-Derived Force Fields for Modeling Hydrocarbon Adsorption in MIL-47(V)

Area of Science:

• Materials Science
• Computational Chemistry
• Physical Chemistry

Background:

• Generic force fields (e.g., UFF, DREIDING) are commonly used for MOFs but their accuracy is uncertain.
• Accurate modeling of molecular adsorption and diffusion in MOFs is crucial for materials design.

Purpose of the Study:

• To develop a general framework for creating transferable force fields for MOFs.
• To accurately model alkane adsorption and diffusion in the nonflexible MIL-47(V) MOF.

Main Methods:

• Utilized periodic density functional theory (DFT) calculations to determine interaction energies.
• Calculated energies for numerous favorable adsorbate configurations to build the force field.
• Validated the force field against adsorption isotherms, heats of adsorption, and diffusion data.

Main Results:

• Developed a transferable force field that accurately predicts adsorption and diffusion properties for various alkanes and alkenes in MIL-47(V).
• Demonstrated the force field's transferability to related MOFs, such as MIL-53(Cr).
• Applied the force field to compute free-energy differences for MIL-53(Fe) phases.

Conclusions:

• The developed framework provides a reliable method for creating accurate, transferable force fields for MOFs.
• This approach enhances the predictive power of simulations for gas adsorption and separation processes in MOFs.