Wang and colleagues by x-ray diffraction with a resolution of 2.5 Ångströms). Then, using the Chimera software , all other than amino acids, such as water and electrolytes, were eliminated. In practice, the separation that allows the molecules to join was found by trial and error. Experiments by MD were carried out starting at a distance of 14 Å and all the way down to 6 Å. For the separation of RBD from ACE2, the Pymol(R) software was used. At distances greater than 6 Å, the attraction between both molecules is so low that, instead of approaching, they move away from each other. At 6 Å (RBD-ACE2-6A), there is a Lennard-Jones Short Range (LJ-SR) potential energy of around -30 KJ/mol, which causes the molecules to always approach each other, until they form a complex with the same properties observed in living systems. This simulation was based on a protocol published by Justin A. Lemkul . This protocol verifies that the crystal proteic structure is correct, and then builds its topology using in this case the CHARM36-julio2020 force field and the TIP3P water model. Notice that during this process GROMACS establishes a neutral PH by default. Then, a single dodecahedron shaped cell is defined, the RBD-ACE2-6A complex is placed inside the cell and then is filled with water, ions are added as neutralizing agents (sodium or chlorine). In order to avoid steric clashes or inappropriate geometry, minimum energy is obtained by MD. The following step is to balance the solvent and the ions around the protein. To perform this, a two phase equilibrium process by MD is employed. The first phase is conducted to a constant number of particles, volume and temperature (NVT). The second phase stabilizes pressure and and is performed on a constant number of particles, pressure and temperature (NPT). Following this procedures, the system is stabilized at 300 • K and 0 Bar. The last step is to run the simulation. Using this protocol, the system was simulated for 100 ns.