RMSD of atomic position is calculated to assess the quality of optimized structures. To calculate the RMSD atomic position of lattice optimized structures, the unit cell is scaled back to the original cell parameters. The average RMSD for all atoms are 0.489Å when atom positions are optimized with the lattice fixed at its experimental value and 0.617Å when the lattice is simultaneously optimized as shown in Table . Oxygens attached to metal atoms have slightly higher RMSD in both cases, but the positions of the metal atoms themselves are slightly better conserved with RMSDs of 0.439Å and 0.560Å for fixed and lattice-optimized structures respectively. Atoms in the organic linker have a higher deviation than the atoms in metal node since the organic linkers have more flexibility and degrees of rotational freedom around the inorganic building unit.