Flexibility windows in faujasite with explicit water and methanol extra-framework content.

We present geometric simulations on a zeolite framework (faujasite) with extra-framework methanol and water contents explicitly present. We distinguish the intrinsic flexibility window of the framework from the newly defined extrinsic window limited by host-guest steric interactions. The extrinsic flexibility window can be limited not only in compression, but also in expansion, as the beta-cages in a maximally expanded framework lack the flexibility to adapt bulky contents such as a combination of methanol and water molecules. Our simulations suggest a reinterpretation of extra-framework content nominally refined as water sites in compression experiments.