Is phosphorus supported?

I get

```
Error from diat.py, overlap matrix
Some elements are not supported yet
```

when trying to use a molecule with phosphorus. Is there a work-around? Thanks.

Start by inspecting the error path named in diat.py, especially the overlap matrix handling, and trace how supported elements are determined. Confirm whether phosphorus can be handled and identify a documented workaround or the required support change; a phosphorus-containing molecule should no longer produce the unsupported-elements error.

Written by the indexing model from the issue text.