First-principles Hubbard U approach for small molecule binding in metal-organic frameworks

Area of Science:

• Computational Chemistry
• Materials Science
• Solid-State Physics

Background:

• Accurate prediction of small molecule binding to transition metal atoms in metal-organic frameworks (MOFs) is crucial for designing materials with specific functionalities.
• Previous computational methods often rely on empirical parameters, limiting predictive accuracy and applicability across different metal centers.

Purpose of the Study:

• To develop and validate a first-principles computational approach for calculating small molecule binding energetics to open-shell transition metal atoms in MOFs.
• To determine accurate Hubbard U values ab initio for various metal centers in M-MOF-74 systems.
• To assess the predictive capability of the method for CO2 binding energies and lattice parameters.

Main Methods:

• Density Functional Theory (DFT) with Hubbard U corrections and van der Waals dispersion-corrected functionals.
• Ab initio determination of Hubbard U values using a linear response procedure.
• Application to M-MOF-74 systems with different transition metal centers (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu).

Main Results:

• Calculated lattice parameters for M-MOF-74 systems show excellent agreement with experimental data (within 3%).
• Ab initio determined Hubbard U values lead to accurate electronic contributions to CO2-MOF binding energies.
• CO2 binding energy in Co-MOF-74 increases monotonically with Hubbard U, demonstrating the method's sensitivity and predictive potential.

Conclusions:

• The first-principles approach with ab initio Hubbard U corrections offers a computationally efficient and accurate method for predicting small molecule binding energetics in MOFs.
• This validated methodology can be reliably used for designing novel MOFs with tailored properties, independent of specific cations or experimental data availability.
• The study provides valuable insights into the relationship between Hubbard U values and gas binding affinities in open-shell transition metal MOFs.