The crystallographic structure of the RBD SARS-CoV-2 plus ACE2 system, with access code 6M0J, was the starting structure for this part of the study. As the S-protein is glycosylated with N-acetylglucosamine (NAG), and due to the high computational cost of mixing the parameters of the force fields of proteins and saccharides, it was decided to eliminate these NAG residues, since they are far from the binding zone with ACE2. Besides, hydrogens were added to the residues of both proteins according to the physiological pH, and the orientation of the side chains was adjusted using the Protein Preparation Wizard workflow included in the Maestro software. For the treatment of the zinc atom present in the ACE2 protein, the dummy cationic approach was used. Using the LeaP module of AMBER20 the system was placed in a cubic box filled with TIP3P water molecules, establishing a minimum distance of 15 Å between the solute and the walls of the box, and those water molecules closer to 2 Å were removed from any atom in the complex. LeaP was also used to add the necessary counterions, in the positions of lower electrostatic potential, to neutralize the system. All calculations were performed using the ff14sb force field with a cutoff of 10 Å for non-covalent interactions. Electrostatic interactions were calculated using the Particle Mesh Ewald (PME) method. 32