Bayesian Optimization (SFBO). Finally, we assess the performance of single-fidelity (SF) BO of COFs for Xe/Kr separations-standard Bayesian optimization with the high-fidelity simulation of Xe/Kr adsorption using, for a controlled comparison to MFBO, (i) the same three COFs for initialization , (ii) the expected improvement acquisition function, Fig. shows the search efficiency curve of SFBO compared to MFBO. SFBO incurred a runtime of ∼315 hr, more than five times that of MFBO (58 hr).