MDI Library enables code interoperability via the MolSSI Driver Interface (MDI). The MDI project, managed by the Molecular Sciences Software Institute, provides a standardized API for fast, on-the-fly communication between computational chemistry codes. This greatly simplifies the process of implementing methods that require the cooperation of multiple software packages and enables developers to write a single implementation that works across many different codes. Warning for Slackware64 users The package openmpi4 reported in MDI_Library.info is strictly needed for Slackware 32-bit system since Open MPI versions greater than 4.1.8 support only 64-bit systems. On Slackware64 you could prefer the package openmpi (based on version greater than 5.0.0). MDI_Library can be built both against openmpi4 or openmpi.