In the control scenario, which allowed to validate the methodology and materials, the RBD should bind to the ACE2 correctly after a certain period of time. That is, the RBD-ACE2 complex would be obtained with binding energies, hydrogen bonds and distances between the two molecules, similar to the results obtained in vivo. However, even for very powerful computers, these simulations become excessively demanding when the molecules are left at random spatial positions before waiting for the correct binding to happen. Therefore, a decision had to be made to place the RBD and ACE2 molecules face-to-face in the precise position where they could join, but separated by a distance that would allow them to form the RBD-ACE2 complex.