I believe I have to put the lattices which are to be used in a solid-state NEB calculation in lower triangular form. From perusing the documentation, it appears that there is a method for a “cell” object to do so (I tried it and it works). As I am not very familiar with ASE, I would like to know how to transform an atoms object (lattice plus atom positions) into standard form. Can anyone offer a simple few lines of code on how to do so?

I believe

```
atoms.set_cell(atoms.cell.standard_form()[0], scale_atoms=True)
```

will work, but would strongly recommend to test that carefully before using in production

I’m afraid that would go wrong for funny Bravais lattices, since the reduction operation implemented by standard_form() is a general 3x3 integer operation with determinant 1 (it could be a permutation), whereas I don’t think set_cell() is capable of expressing a permutation.

You would need something along the lines of `make_supercell()`

and then pass the 3x3 integer operation to that.

(Well, we’re not talking general lattice reduction, only mapping the directions to upper/lower. So *maybe* it works, but most of the reduction functions have cases where they probably don’t, so I’d just advise to be careful)

(Actually sorry, I confused this operation with the others like Niggli/Minkowski, but this one only performs a rotation which is then not an integer matrix. Thus my comments above don’t apply)