It would be inconsistent if the host-host contribution would be ignore. The large value is because you have a lot of VDW pairs in the framework.
Note: if a particle moves from A to B, in the energy difference that value cancels out. So it has little influence on adsorption, only via the positions of the framework atoms.
Note: if a particle moves from A to B, in the energy difference that value cancels out. So it has little influence on adsorption, only via the positions of the framework atoms.