Expand the ECP basis library

[robashaw]

The ECP library is currently quite sparse, comprising primarily just the fully relativistic Stuttgart-Dresden ECPs (ECPnMDF). It would be very convenient to have as many ECPs standardised directly in the library as possible, especially as there is often confusion over conventions with regards to the power of n (e.g. 0, 1, 2 vs. -2, -1, 0)

There are two main things to do here:

• scrape ECPs from wherever possible, e.g. the BSE;
• write new wrappers in share/libecpint/parseecp.py so that other ECP formats can be converted, currently it's just one of the two (!) MOLPRO formats

[peterbygrave]

I have a library in development that might help here. It embeds BSE in to library with C++ class/struct representation matching the BSE JSON schema.

It's current private repo as I haven't had enough time to finish everything for release. If you are interested I can send you an invite to preview the repo. Would be great to offer something back as we have enjoyed having your library in Entos/Qcore.

[robashaw]

That would be great, please do send an invite. Or if you'd rather wait until you're sure it's ready, I'm unlikely to be working on this for a little while, so don't feel there's any rush.

[peterbygrave]

Okay ping me when this becomes a blocker and I'll try to have it ready/public ASAP.