Subsystem density‐functional theory (update)

The past years since the publication of our review on subsystem density‐functional theory (sDFT) (WIREs Comput Mol Sci. 2014, 4:325–362) have witnessed a rapid development and diversification of quantum mechanical fragmentation and embedding approaches related to sDFT and frozen‐density embedding (FDE). In this follow‐up article, we provide an update addressing formal and algorithmic work on sDFT/FDE, novel approximations developed for treating the non‐additive kinetic energy in these DFT/DFT hybrid methods, new areas of application and extensions to properties previously not accessible, projection‐based techniques as an alternative to solely density‐based embedding, progress in wavefunction‐in‐DFT embedding, new fragmentation strategies in the context of DFT which are technically or conceptually similar to sDFT, and the blurring boundary between advanced DFT/MM and approximate DFT/DFT embedding methods. This article is categorized under: Electronic Structure Theory > Density Functional Theory Subsystem DFT offers highly efficient, fully quantum‐chemical descriptions of molecular properties for embedded systems, such as chiroptical properties of a chiral molecule (ibuprofen, blue) in a solvent cage (ethanol, orange).