Periodic Density Functional Theory (PDFT) Simulating Crystal Structures with Microporous CHA Framework: An Accuracy and Efficiency Study

The structure property is the fundamental factor in determining the stability, adsorption, catalytic performance, and selectivity of microporous materials. Seven density functional approximations (DFAs) are used to simulate the crystal structure of microporous material for examining the efficiency and accuracy. In comparison with the existing zeolites, microporous materials with CHA framework are selected as the testing model. The calculation results indicate that the least lattice volume deviation is 5.18/2.72 Å3 from PBE_mGGA, and the second least is −5.55/−10.36 Å3 from LDA_PP. Contrary to USPP_LDA, PBE_GW, PAW_PBE, and PAW_GGA overestimate the lattice volume by ~15.00–20.00 Å3. For each method, RMS deviations are less than 0.016 Å for bond length and less than 2.813° for bond angle. To complete the crystal structure calculation, the CPU time reduces in order of USPP_GGA > PBE_GW > PAW_GGA, PBE_mGGA > PAW_PBE > LDA_PP > USPP_LDA. For two testing models, when the calculation time is not important, PBE_mGGA is the best choice, and when the tradeoff between accuracy and efficiency is considered, LDA_PP is preferred. It seems feasible and efficient to simulate the zeolite structure through E-V curve fitting, full optimization, and phonon analysis bythe periodic density functional theory.

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