Relativistic Prolapse-Free\nGaussian Basis Sets of\nDouble- and Triple‑ζ Quality for <i>s</i>-\nand <i>p</i>‑Block Elements: (aug-)RPF-2Z and (aug‑)RPF-3Z

This study presents two new relativistic Gaussian basis\nsets without\nvariational prolapse of double- and triple-ζ quality, RPF-2Z\nand RPF-3Z, along with augmented versions including additional diffuse\nfunctions, aug-RPF-2Z and aug-RPF-3Z, which are available for all <i>s</i> and <i>p</i> block elements from Hydrogen to\nOganesson. The exponents of the Correlation/Polarization (C/P) functions\nare obtained from a polynomial version of the generator coordinate\nDirac–Fock method (p-GCDF). The choice of C/P functions was\nguided by multireference configuration interaction calculations with\nsingle and double excitations (MR-CISD) based on a valence active\nspace. Finally, calculations of fundamental properties done for atomic\nand molecular systems (bond lengths, vibrational frequencies, dipole\nmoments, and electron affinities) ensure the expected quality of these\nnew basis sets, which may also exhibit some computational efficiency\nadvantages. Additionally, the prolapse-free feature of these sets\nmust provide a reliable description of properties more dependent on\ncore electron distributions, as well.