Geometry optimization with periodicity?

General Discussion
1

Hello,

would it be please possible to have geometry optimization with periodicity included ? Let say, optimization of crystal structures.

2

Right now, Avogadro heavily uses Open Babel for geometry optimization, which doesn’t (yet) have any periodic force fields.

I’m working on a new plugin system for geometry optimization, which will allow periodicity.
(e.g., you’ll be able to write a bit of Python glue to use other programs for energies, forces, etc. - and get the unit cell parameters).

Is there a particular program you’d use for optimization of periodic structures?

1 Like
3

Thanks for your reply. I like force fields for fast geometry optimizations, what is very suitable for teaching purposes. So, after Avogadro I would prefer MOPAC.

4

You might also want to check out xtb from the Grimme group. I haven’t evaluated the periodic capabilities, but it’s similar to DFTB so it’s also very fast.

Many of these codes can work through ASE, which will also be supported in Avogadro v2.

1 Like
5

Well, how about https://avogadro.cc/teaching/hydrogen_cluster/ ? How did he get the UFF cell parameters ?

6

IIRC he did that manually.

The new forcefield framework definitely supports this. I’d be happy to work through some example plugins. ASE? XTB? What codes do you currently use for this?

At the moment, optimizing the lattice parameters isn’t handled, but I can work on that over the next few weeks … unless you know some codes that return gradients on the lattice vectors.