A straightforward approach for evaluating the interaction energy is to calculate the difference between the objects' combined energy and all of their isolated energies. In the case of two objects, A and B, the interaction energy can be written as: Δ Δ E int = E ( A , B ) − − ( E ( A ) + E ( B ) ) , where E ( A ) and E ( B ) are the energies of the isolated objects (monomers), and E ( A , B ) the energy of their interacting assembly (dimer).