How to find the global minimum...?

I would like to find out the global minimum of a guest molecule within the pore of a MOF. I know I can place the guest molecule in the pore and get the host-guest structure optimized, but if I would place the guest molecule in another position of the same pore, there also I can get the structure optimized. In this scenario how could I find the exact most probable location of the guest molecule within the MOF pore or its global minimum...?

Any help would be highly appreciated...

-Monu