Enable getting basis sets through BSE library

[bennybp]

Description

This PR allows for using basis sets from the Basis Set Exchange library (https://github.com/MolSSI-BSE/basis_set_exchange) directly in psi4.

To use a basis set from the BSE, you prefix the name of the basis set with bse:. Optionally, you can specify the version with a suffix (like :1)

# use most recent def2-tzvp version
set basis bse:def2-tzvp

# specifically use version 0 of sto-3g
set basis bse:sto-3g:0

Also can be used with assign

basis  {
   assign DZ
   assign C bse:sto-3g:0
}

Using these of course requires that the BSE be installed. This should be accessible from both schema/json and psithon.

User API & Changelog headlines

• Add capability to use basis sets from the Basis Set Exchange

Dev notes & details

• Adds optional dependency to basis_set_exchange
• Adds handling for basis sets that start with bse:
• Modifies some regexes to allow for colons in basis set names

Questions

None

Checklist

• Optional dependency added to build chain
• Tests added for any new features
• All or relevant fraction of full tests run

Status

• Ready for review
• Ready for merge

[JonathonMisiewicz]

Why does refscf disagree between mints2-bse and mints2?

[loriab]

Why does refscf disagree between mints2-bse and mints2?

I think Ben mentioned to me that it's because of revision of the basis set, and if a :0 (equals old PNNL BSE) version is used they match exactly.

[JonathonMisiewicz]

The output file included in the PR uses :0 but is still showing disagreement with mints2. (The input and output files have different reference energies, which is more confusing.)

[loriab]

The "base" basis changed, too, from DZ to 6-31g. Only one atom left with it, if I'm reading it right.

mints2 (usual)

   # First, assign DZ to all atoms
   assign DZ
   # Now, assign 3-21G to all carbon atoms
   assign C my3-21G
   # The two atoms labelled H1 get a STO-3G basis two
   assign H1 sto-3g
   # Carbons 3 and 5 get a STO-3G basis, too
   assign C1 sto-3g

mints2-bse

   # First, assign DZ to all atoms
   assign bse:6-31g
   # Now, assign 3-21G from bse library all carbon atoms (latest version)
   assign C bse:3-21g
   # The two atoms labelled H1 get a STO-3G basis from psi4 library
   assign H1 sto-3g
   # Carbons 3 and 5 get a STO-3G basis from BSE, but specify v0
   assign C1 bse:sto-3g:0

[JonathonMisiewicz]

Thanks. In that case, can we change the comment at the start of the file to mention that? As written, I thought the two energies were supposed to be identical.

[loriab]

Thanks. In that case, can we change the comment at the start of the file to mention that? As written, I thought the two energies were supposed to be identical.

Sounds good. This is why I like parameterized pytest for seeing the input differences.

@bennybp, did I get the why-different reasons right above? And if you're changing that comment, maybe regenerate the ref file w/o test fail:

https://github.com/psi4/psi4/pull/2905/files#diff-667f7008a6b3ab105b3130447305716990d91451c161ed7eaf1f04886bd32a00R361

[bennybp]

Well that was sloppy of me. Thanks for catching that

[JonathonMisiewicz]

I'm letting @loriab merge, since she's more familiar with MolSSI interfaces.