Towards rapid computational screening of metal-organic frameworks for carbon dioxide capture: Calculation of framework charges via charge equilibration

Metal-organic frameworks are promising materials for the capture of carbon dioxide. Finding the best metal-organic frameworks from the vast number of possibilities could be greatly accelerated by efficient computational screening techniques. We have previously reported an effective screening protocol for predicting carbon dioxide adsorption performance in metal-organic frameworks that uses grand canonical Monte Carlo simulations of gas adsorption. In the model, molecules interact via van der Waals and electrostatic interactions with each other and the framework. However, the method requires single-point quantum mechanics calculations for the estimation of atomic partial charges. In this study we investigate the feasibility of a modified protocol that bypasses the computationally expensive quantum mechanics calculations by applying instead the charge equilibration method. We compare the results of both protocols directly on fourteen metal-organic frameworks and conclude that the new protocol is sufficiently accurate for screening purposes and is significantly faster.