Our DFT calculations, which were based on more ordered distribution of capping ligand, being either formate, hydroxide, or hydroxide with water, show that the interlayer spacing, which determines the lattice parameter along the c axis, is very sensitive to the identity of the capping unit. We found that replacing formate by hydroxide in these models led to a significant contraction in the c axis, from 14.20 Å to 12.88 Å (10%), of comparable magnitude to that found on desolvation of the experimental GUF-14. We note the experimentally determined lattice parameter along the c axis for the desolvated sample is 14.486 Å, which is a result of spatial averaging from the Pawley refinement, and there may be local regions in the sample with bigger or smaller interlayer spacing, i.e., closer to what we see in our DFT calculations with hydroxide or hydroxide/water as capping unit. Additional DFT calculations of the alternative 'AB' type stacking show that the two stacking sequences are comparable in energy, with the energy difference depending strongly on the identities of both capping ligands and guests (EAB-EABC = -10.6 kJ mol -1 per Zr6 cluster for formate capping, -52.9 kJ mol -1 per Zr6 cluster for hydroxide capping, and +91.1 kJ mol -1 per Zr6 cluster for hydroxide capping with guest water), providing further evidence for the feasibility of the stacking faults postulated from PXRD analysis.