“…Recently, it has even been argued that no such solutions may be formulated for comparably simple systems such as the He atom. 2 While routine applications in quantum chemistry rely on numerical frameworks such as Hartree-Fock (HF) [3][4][5][6] and post-HF 6,7 apa Theoretical Chemistry, Division, Institute of General, Inorganic and Theoretical Chemistry, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria. E-mail: t.hofer@uibk.ac.at b Research Institute for Biomedical Aging Research, University of Innsbruck, Rennweg 10, A-6020 Innsbruck, Austria † Electronic Supplementary Information (ESI) available.…”