Chemist: A Domain-Specific Language by Chemists for Chemists

Managing the complexity of quantum chemistry (QC) software
is key
to ensuring it remains accessible, maintainable, and reusable. Noticeably
missing from the QC ecosystem are modules targeting bottleneck routines.
Here we argue that this is likely due to the difficulty in defining
interfaces for such modules. To that end, we introduce the open-source,
publicly available Chemist library https://github.com/NWChemEx/Chemist. Chemist is a domain-specific language targeting
the QC domain. Chemist has been developed focusing
on performance and user-friendliness. Using Chemist, QC tasks are defined using familiar domain concepts such as molecules,
wave functions, and operators. The domain objects are hierarchical
to ensure a systematic encapsulation of information. Key features
of Chemist include: extensibility, the ability
to alias existing data, and the ability to succinctly define many
common QC tasks. The usefulness of Chemist is
demonstrated by discussing the interface of NWChemEx’s Fock build module and by showcasing a proof-of-concept
self-consistent field algorithm containing uncertainty propagation.