Standardizing Code Interoperability Through the MolSSI Driver Interface Project*

The MolSSI Driver Interface (MDI) Project provides a standardized API for fast, on-the-fly communication between software in the computational molecular sciences domain.  The API is sufficiently general to support a wide variety of techniques, including QM/MM, ab initio MD, machine learning, advanced sampling, and path integral MD, while also being straightforwardly extensible.  Furthermore, the MDI project's flexible API enables codes to interact at multiple different points throughout a simulation; this effectively allows MDI-enabled codes to insert callback functions that can modify behavior at a lower level than what is possible through a typical library API.  The details of inter-code communication are handled by the MDI Library, which supports tight coupling via MPI, TCP/IP sockets, or through a plugin interface.  With support in a growing number of codes, MDI offers developers an opportunity to create general interfaces that ensure their codes can be easily interoperated with other software in modular manner.