Is it possible to use CE in ionic crystals?

[MilitaoLucas]

Is the new version compatible with ionic crystals? I would guess that maybe the Tonto backend was the problem?

[peterspackman]

Might need a bit more clarification what you mean here.

For ionic molecular crystals:
If you mean energy calculations: they always worked with ionic crystals (minus some bugs, but the bugs with mapping wavefunctions occurred for all crystals, just that ionic crystals must have at least two different components so you saw them more often), but things like lattice energies as sums of pairwise interactions are a poor approximation for the real results.

If you mean surfaces, other properties etc. then, again , they always worked (though the choice of the promolecule density atomic wavefunctions may not be appropriate for small ions, atomic ions should use the appropriate charge).

For non-molecular crystals such as MOFs, inorganic materials:
Much of the functionality in CE assumes you're dealing with a crystal that can be divided into molecules. The bonding guesses will likely be wrong (but can be overridden as of recent versions) and then the behaviour of e.g. expanding out in clusters etc. should work, but the behaviour for e.g. 'completing' molecules will not necessarily be what you'd expect for a bonded framework.

The energy models of course are not applicable to frameworks or inorganic crystals really, likewise computing gas-phase wavefunctions doesn't really make a good approximation for these systems.

In short - yeah it works, but the usefulness will depend on the crystal and problem you're trying to solve.

[MilitaoLucas]

I get it now. Thank you for the information. Did you write a paper on it, or is there some resource you could recommend for further reading? I think this clarification is pretty good.

[peterspackman]

Some of the info is scattered in the papers/documentation, but it could definitely be better accessible (as with most of this stuff) I just find I don't have a lot of time to write good documentation.

[MilitaoLucas]

No problems. I will hunt for it. Thank you anyway.