Better Electron Models Boost Materials and Machine Learning
Scientists are continually refining density functional theory, a cornerstone of modern electronic structure calculations used across chemistry, physics, and materials science. Fabien Tran from VASP Software GmbH, Susi Lehtola from the University of Helsinki, Stefano Pittalis from Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, and Miguel A. L. Marques from Ruhr University Bochum, working in collaboration with all four institutions, have comprehensively reviewed semi-local exchange-correlation functionals, vital approximations used to model electron interactions within this theory. This research is significant because, despite decades of development yielding hundreds of approximations, a clear and consistently organised overview of these semi-local functionals has been lacking, hindering both accessibility for newcomers and advanced application by experienced researchers. Their work consolidates historical developments and recent advances, offering a unified framework to guide future improvements in density functional approximations and broaden their application to complex scientific challenges. Six decades of effort have yielded hundreds of approximations to understand how electrons interact within materials — despite this extensive work, accurately modelling these interactions remains a central challenge in chemistry and physics. This review offers a unified framework to guide future development of these essential computational tools, and scientists have long relied on density functional theory (DFT) as a cornerstone of modern electronic structure calculations. A method with broad applications spanning chemistry, physics, materials science, and biochemistry. At the core of DFT lies the exchange-correlation functional, a mathematical quantity that accounts for the complex interactions between electrons within a material. To determine the exact form of this functional remains an unsolved problem, necessitating the use of approximations to make practical cal
