A database of molecular properties integrated in the Materials Project

Advanced chemical research is increasingly reliant on large computed datasets of molecules and reactions to discover new functional molecules, understand chemical trends, train machine learning models, and more. To be of greatest use to the scientific community, such datasets should follow FAIR principles (i.e. be findable, accessible, interoperable, and reusable). In this work, we present a FAIR expansion of the Materials Project database ("MPcules") that adds more than 170 000 molecules studied using density functional theory (DFT) to the existing data, which comprises crystalline solids. MPcules is a diverse collection of DFT-calculated molecular properties, with an emphasis on reactive, open-shell, and charged species-relevant for studying reaction pathways-and a wide array of structural, electronic, vibrational, and thermodynamic properties. This database can be queried through an OpenAPI-compliant application programming interface and a featureful web application. We continue to expand the data available on MPcules and encourage contributions from the community. A new infrastructure for computed molecular properties, including a web app and API, is incorporated into the Materials Project, enabling the creation of a database currently containing over 170 000 molecules.