Zero and finite temperature adsorption energies in zeolites: A random phase approximation study

Zeolites are widely used in industry as sorbents and catalysts due to their porous structures that can host various ions and molecules [1]. Adsorption of molecules in zeolites is typically determined by van der Waals (vdW) forces. This represents a challenge for ab-initio calculations, since semi-local approximations based on the density functional theory (DFT) fail to include vdW interactions. The random phase approximation (RPA) is an ab-initio scheme to build a fully non-local correlation functional that accurately captures vdW forces. The RPA can today describe realistic systems with a few hundreds of electrons and generate accurate benchmarks. Using the RPA as implemented in Refs. 2-3 we compute adsorption energies of methane and carbon dioxide in siliceous chabazite at 0 K. To evaluate temperature effects on the interaction energy we average over multiple configurations generated by molecular-dynamics simulations at 300 K. These results are compared with those obtained using DFT approximations with semi-empirical corrections.[1] S. Auerbach, K. Carrado, P. Dutta, Handbook of Zeolite Science and Technology, CRC Press (2003) [2] D. Rocca, J. Chem. Phys. 140, 18A501 (2014) [3] A. Dixit, J. Angyan, D. Rocca, J. Chem. Phys. 145, 104105 (2016)