Segmented Contracted Error-Consistent Basis Sets of Double- and Triple-ζ Valence Quality for One- and Two-Component Relativistic All-Electron Calculations.

Segmented contracted Gaussian basis sets optimized at the one-electron exact two-component (X2C) level - including a finite size model for the nucleus - are presented for elements up to Rn. These basis sets are counterparts for relativistic all-electron calculations to the Karlsruhe "def2" basis sets for nonrelativistic (H-Kr) or effective core potential based (Rb-Rn) treatments. For maximum consistency, the bases presented here were obtained from the latter by modification and reoptimization. Additionally we present extensions for self-consistent two-component calculations, required for the splitting of inner shells by spin-orbit coupling, and auxiliary basis sets for fitting the Coulomb part of the Fock matrix. Emphasis was put both on the accuracy of energies of atomic orbitals and on the accuracy of molecular properties. A large set of more than 300 molecules representing (nearly) all elements in their common oxidation states was used to assess the quality of the bases all across the periodic table.