Our approach is based on the formulation of Bjornsson and Bühl. To the best of our knowledge, the latter authors were the first to propose calculations of molecular crystals with a central QM system surrounded by a polarizable explicit MM structure. The idea is rather straightforward. The unit cell is singled out and a quantum mechanical calculation is executed for the molecules therein contained. Partial charges are derived from the latter calculation and then placed in space to replicate a crystal environment. Lennard-Jones potentials are used to describe weak forces and repulsion between the environment and the QM system. Under the influence of the electrostatic field a new quantum mechanical calculation is carried out, resulting in a new density which is again used to compute embedding charges. The procedure is repeated till self-consistence is reached. From this point onward the crystal embedding environment is kept frozen (both the geometries and the charges) and the molecules within the unit cell are optimised under these conditions. It is a method primarily geared for weakly interacting molecules in a crystal.