What's a general algorithm to build a supercell from a primitive cell?

In summary, the conversation discusses the use of code to compute the structure factor of a basis and the desire to incorporate subtle differences between atoms. This requires computing the structure factor of a supercell instead of a primitive cell. However, there is uncertainty about the algorithm for determining the new lattice translation vectors and the inclusion of basis atoms to avoid overlap. The conversation concludes with the acknowledgement that there is no single defined algorithm for designing a supercell.
  • #1
SadScholar
36
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Basically, I've written some code that take as inputs 1)Basis vectors 2)lattice translation vectors
and computes the structure factor of the basis, producing a diffraction pattern.

I'd like to begin incorporating subtle differences between atoms, so I want to compute the structure factor of a supercell instead of a primitive cell. So for instance, let's say I'm dealing with graphene. That lattice has a 2-atom basis, so a supercell would be built of maybe 4 or 6 atoms. The thing is, I'm not sure what algorithm determines the new lattice translation vectors. If these aren't chosen correctly, it messes up the reciprocal space and diffraction condition.

Ideally there should be some general, bravais-lattice-independent method of building the supercell so that the supercell lattice vectors are just multiples of the primitive lattice vectors, but I don't know which basis atoms to include to avoid overlap upon translation. Any tips or references would be greatly appreciated.
 
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  • #2
There are many many possible supercells that can be found in surface science, magnetism, crystallographic phase transitions etc. I don't think that there is a single defined algorithm for designing "the" supercell.
 

What is a primitive cell?

A primitive cell is the smallest repeating unit in a crystal lattice, which contains all of the necessary information to describe the entire crystal structure.

What is a supercell?

A supercell is a larger unit cell that contains multiple primitive cells, allowing for the simulation of larger and more complex crystal structures.

Why is it important to build a supercell from a primitive cell?

Building a supercell from a primitive cell allows for a more accurate representation of the crystal structure, as it takes into account the interactions between multiple primitive cells.

What is the general algorithm for building a supercell from a primitive cell?

The general algorithm involves replicating the primitive cell in all three dimensions, scaling the lattice vectors and atomic coordinates accordingly, and then adjusting the atomic positions to eliminate any overlapping atoms.

Are there any limitations to this algorithm?

Yes, there are limitations to this algorithm, as it may not accurately represent certain crystal structures with complex symmetries or interactions. Additionally, the size of the supercell may be limited by computational resources.

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