# Tag Info

9

In the experiment, you can always put two semiconducting crystal layers together. For DFT simulation, you can also stack two semiconducting crystal layers together, but you must consider the lattice match. For example, monolayer MoS$_2$ and monolayer WS$_2$ can be stacked directly because these two monolayers have almost the same lattice constant. But if ...

8

Since the constituent monolayers have generally differing lattice constants, special care is needed in the construction of the atomic models in such a way that the strain is minimized. Let us denote the primitive cell basis vectors of a hexagonal 2D material $i$ as {$a_i$,$b_i$}. The supercell basis vector may be constructed as $n_ia_i$+$m_ib_i$, where $n_i$...

6

I believe what you are referring to is a "projected" or "fat" band structure diagram. By assigning colors (or line thickness) to a basis on which you project the Kohn-Sham states (pseudoatomic orbitals, Wannier functions, etc.) you can plot the band structure in a way that shows the composition of all the states in the bands in terms of ...

6

Speaking as someone who does both computational modeling and experiment, there is not a trivial answer! I'm not sure if you are referring to 2D materials (which Jack addressed in his answer) but I am not experienced with that, so I will try to answer in the context of general thin films. In experiment, you can of course deposit films on any substrate you ...

5

This may be a bit of a rough answer, so apologies in advance... Since the eigenvalues obtained using non-energy-consistent pseudopotentials (i.e. the situation in VASP as far as I know) do not themselves have physical meaning, we typically use a slab system with an explicit vacuum, in order to make reference to vacuum. A more common situation is calculating ...

5

Since we focusing on matter modeling I would try to provide a method a general method of actually creating these models. As others have mentioned, you will need to deal with the problem of mismatching lattices. This can be deal with by either directly stretching the lattice of one material to match the other and simply stacking them or we can make a model ...

4

Not a fully GUI solution but if we can assume you get a primitive cell to work with, Atomic Simulation Environment can generate your surface. For some extra spice, its common to want to make root surfaces such as $\sqrt{2}$x$\sqrt{2}$, so I included a final step which will do this assuming there is a valid $\sqrt{2}$x$\sqrt{2}$ to make. There is also a ...

3

The electronic band structure is a concept for periodic system. Heterostructures are not periodic system (in the direction of heterostructure grow). What is done is an approximation where the bulk's band of each bulk system is combined using the band off-sets. Some reference about how to calculate band off-sets are: Theoretical calculations of ...

2

Two things are important for the computational speed for VASP users. The first thing is ENCUT, which is controlled by the INCAR file. For a quick calculation, you can pick up this value just by referring to the ENMAX values of your POTCAR file. The other thing is the k sampling, which is decided by KPOINTS file. For your system with 60 atoms, I guess your $a$...

1

I think Camps gives a mostly correct answer for this. I will say though, it may be possible in some cases to generate a band structure in the direction of the heterostructure by making a periodic bulk heterojunction. By layering two materials with minimal (or large if intended) strain in a bulk system with bulk crystal structure, you may get some ...

1

Make a supercell of both the unit cells, so that they fit on top of each other.

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