In the first configuration, which is energetically slightly favoured according to DZVP results, the 5-FU molecule lies more or less flat above one 6MR and one 4MR forming the wall of the FAU supercage. As no hydrogen bonds are present, it can be concluded that the molecule interacts with the zeolite predominantly through dispersion interactions. In the second configuration, more favourable according to the calculation using TZVP basis sets, the molecule assumes a more tilted orientation with respect to the curvature of the pore wall, forming a relatively long hydrogen bond via the H1 atom to a framework oxygen atom (Ofw). AIMD simulations starting from both configurations (two from Config1, two from Config2) resulted in fairly similar RDFs.