All-electron double zeta basis sets for the most fifth-row atoms: Application in DFT spectroscopic constant calculations

Segmented all-electron contracted double zeta valence plus polarization function (DZP) basis sets for the elements Cs, Ba, La, from Hf to Ir, and from Au to Rn are constructed for using in conjunction with the non-relativistic and Douglas–Kroll–Hess (DKH) Hamiltonians. Using the B3LYP hybrid functional, the performance of the DZP–DKH basis set is assessed for predicting atomic ionization energy as well as spectroscopy constants of some compounds. Despite its compact size, this set demonstrates consistent, efficient, and reliable performance and will be especially useful in calculations of molecular properties that require explicit treatment of the core electrons.