MolSSI Announces the New Basis Set Exchange

The MolSSI and the Environmental Molecular Sciences Laboratory (EMSL) are proud to announce a beta release of a new Basis Set Exchange (BSE –  This collaborative effort is an update of the original Basis Set Exchange with new features and updated/revised data.  The goal of this project is to create a consistent, thoroughly-curated database of basis sets, provide a standard nomenclature for quantum chemistry basis sets, and provide multiple methods for accessing the basis sets.

Pople, Dunning, Ahlrichs, STO and several fitting basis sets as well as the CRENBL, LANL and def2 ECPs are currently available. More of the original BSE basis sets will be available in the future.

Features of the new BSE include:

  • Access to the Gaussian basis set libraries through
    • Locally-installed Python library with command-line interface
    • Public REST APIs
    • Web frontend
  • Updated web frontend
    • Similar look and feel as the original BSE
    • Help pages
    • Select/deselect all elements for a particular basis set
    • Download selected or all basis sets as a file
  • Version control on the basis sets
    • Original BSE basis sets are kept as version 0
    • Updated basis sets, verified against authoritative sources as version 1
  • Updated references in BibTeX and JSON formats (more formats coming soon)
  • Open-source library available on GitHub (
    • Use of GitHub to enable modifications and conflict resolution
    • Ability to download the full basis set library

In addition to these new features, we strongly encourage the community to contribute additional basis sets and features through the typical GitHub pull request procedures, or by e-mail to core developers Ben Pritchard and Doaa Altarawy at Users can also contribute ideas for new features using GitHub issues.

We thank community members Grant HillArnim HellwegFrank Jensen, and Lori Burns for contributing basis sets and advice on the development of this beta version.