Application of Classical DFT for Screening of MOFs for CO2 Capture
Yun Tian, Jia Fu, Shijie Sheng and Jianzhong Wu
Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA
Due to the widespread public concern of increasing CO2 emission in the atmosphere, CO2 capture has been one of the most urgent issues. With the large gas adsorption capacity and tunable structural properties of MOFs, numerous computational efforts have been dedicated in recent years to examine the performance of MOFs for carbon capture and sequestration from different gas mixtures. Compared with adsorption of LJ fluids (e.g. noble gases, hydrogen and methane) with no charge interactions with MOFs, the long-range Coulombic interactions are crucial for CO2. Despite various methods for extracting atomic charges from the results of quantum mechanical (QM) calculations, performing the GCMC explicitly dealing with long-range Coulombic interactions at each step of simulation for thousands or even millions of MOFs may not be feasible.
To achieve the high-throughput screening of MOFs for CO2 adsorption, we apply the classical density functional theory (DFT) combined with MHNC-RISM to efficiently solve for the site direct correlation functions as the input for DFT calculation. DFT methods have been proven to be much more efficient than simulations in the material screening for hydrogen and methane storage in MOFs with comparable accuracy with GCMC. Within the framework of site-DFT calculations developed for solvation, the long-range electrostatic interaction with full Ewald treatment will only need to be considered once for each material at zero loading, which will be much more efficient than the conventional GCMC calculations. In combination of semi-empirical schemes for the assignment of partial charges and molecular force fields, the computational efficiency of classical DFT makes it a promising tool for design of new MOFs in application to CO2 capture.