In the diagrams, A...B* denotes the co-adsorbed state of species A and B, and A* + B* denotes the infinite separations with each adsorbate (A* or B*) in separate unit cell at its most stable position.
Whether the difference value of EA…B* and EA* + EB* can be calculated in following equation:
E = EA…B* + E* - EA* - EB*
EA…B*:A…B co-adsorption energy
E*:surface with no molequle adsorption
EA*:A single adsorption
EB*:B single adsorption
Additionally, can you explain last step in the Fig.1 ?