The high-fidelity simulation constitutes a Markov chain Monte Carlo (MC) simulation of the system under the BGC ensemble governed by the probability distribution in eqn. 17. Our microstate transition proposals include random adsorbate insertions and deletions, translations, reinsertions, and identity swaps, with acceptance rules dictated by Metropolis-Hastings. Our BGCMC simulation constitutes 500 Monte Carlo cycles (defined as x microstate transition proposals, with x = max(20, n Xe + n Kr )) per Å 3 volume of the system. We discard the first half of the cycles for burn-in.