The computational cost, measured in run time, of a high-fidelity BGCMC simulation of Xe/Kr adsorption in a given COF is greater than the sum of the costs of the two low-fidelity Henry coefficient calculations, i.e. τ (2/3) > τ . First, a single Monte Carlo state transition tends to be more computationally expensive for the BGCMC simulation because, in contrast to the Henry coefficient calculations, generally (i) multiple adsorbates are present in the system and (ii) adsorbateadsorbate interactions are included. Second, the high-fidelity BGCMC simulation must explore a more voluminous state space than the Henry coefficient calculation in order to compute a reliable average. Of course, this cost comparison depends on the number of MC cycles/insertions dedicated to each simulation; we allocated 500 cycles/insertions per Å 3 volume of the system in an attempt to grant each simulation with reasonably comparable errors in the average n . N.b., with further approximation, the computational expense of the Henry coefficient calculations can be reduced by biasing the samples of adsorbate configurations to lie nearby the internal surface (pore walls) of the COF. 112