All-electron basis sets for heavy elements

All-electron (AE) calculations for chemical systems containing atoms of elements beyond krypton are becoming increasingly accessible and common in many fields of computational molecular science. The type, the size, and the internal construction of AE basis sets for heavy elements depend critically on the level of quantum chemical theory and, most importantly, on the way relativistic effects are treated. For this reason, general-purpose basis sets for heavy elements are rare; instead, different AE basis sets have been developed that are adapted to the requirements and peculiarities of each (approximate) relativistic treatment. Ranging from fully relativistic four-component approaches to more popular scalar relativistic approximations, today there exist complete families of AE basis sets that can cover most research needs and can be employed in diverse applications for the proper description of various molecular and atomic properties including electronic structure, chemical reactivity, and a wide range of spectroscopic parameters. For further resources related to this article, please visit the WIREs website.