How to calculate formation energy of a heterostructure?

[farah_shahzadi]

Dear Everyone,

I hope everyone is in good health. I have questions related to formation energy. How can I calculate formation energy of a heterostructure. For example. Ti3C2/graphene. How can I calculate its formation energy ?
After calculating the formation energy if it is positive should we continue our research for battery anode materials ?
If considering a bulk for calculating formation energy as I read somewhere. There are many cif files available for Carbon and other materials more than 3. Which one to choose ?

And how can we say that the crystal is stable for further calculations ?

Any help will be appreciated

[henrique_miranda]

I moved this question from "Using VASP" to from users to users since this a more general physics question and not one about VASP in particular.
Perhaps some other users with experience in this type of calculations can help you.

I can only point out some things that you might need to consider:

1. The formation energy is the difference of total energy of your system and its constituent parts. In your example, you would probably make one calculation of the heterostructure and obtain E_tot, the graphene layer and obtain E_graphene and then Ti3C2 and obtain E_Ti3C2. The formation energy E_form = E_tot - E_graphene - E_Ti3C2.

2. You might need to consider carefully how the heterostructure is lattice matched: the lattice parameters of graphene might be very different from E_Ti3C2 so you might need to strain the two unit cells to match them or perform a supercell computation with some kind of Moiré pattern. This, of course, makes the whole problem much more complicated because there are many ways to match two lattices.