Here, the first term on the right-hand side corresponds to the DFT total energy obtained from a structure optimisation of Org adsorbed in the pores of the zeolite (adsorption complex), where only the atomic positions of the adsorbate were optimised (see below). The second term is the single-point energy of the guest-free zeolite framework, and the third term corresponds to the energy of the optimised, isolated contaminant molecule.