A key challenge for DAC lies in identifying materials that exhibit strong CO₂ affinity and high selectivity over H₂O. To address this, Monte Carlo (MC) simulations such as Widom insertion and Grand Canonical Monte Carlo (GCMC) are used to determine gas adsorption properties of materials by calculating the heat of adsorption (Qst) and Henry's law coefficient (KH). These ensemble-averaged properties enable a more comprehensive evaluation than relying solely on single configuration properties such as adsorption energies at the most likely stable binding sites.