I want to calculate the work of separation between layers of a structure as I have attached from the literature. I know how to calculate at the interface but How about a layer below the interface or at different layers other than the interface? The literature only provided the equation for calculating at the interface but not beneath the interface. Where the up and bottom layers are metal and oxide layers. Thank you.
After a long search I finally found the answer I've been looking for. To calculate the work of separation beneath the interface or at any layer you insert a small vacuum for example 5 Angstrom and calculate the total energy of the system. The work of separation is then the difference between the energy of the separated and the unseparated layers divided by the interface area.