SARC all-electron scalar relativistic basis sets

Design philosophy

DKH2-ZORA radial distribution differences

Exponents are derived from relatively simple rules, using radial expectation values from accurate atomic calculations as generator quantities. The SARC basis sets are more flexible than non-relativistic basis sets in the core region and hence better adapted to relativistic Hamiltonians. Polarization function sets are available for DFT and (for some elements) also for correlated wave function methods. Contraction coefficients are optimized separately for the DKH2 and ZORA Hamiltonians. This is necessary because the two Hamiltonians behave differently close to the nucleus, e.g. the ZORA potential is more attractive, producing tighter core orbitals. A useful overview of basis sets for heavy elements can be found here.

Typical applications

Development status

Currently the SARC basis sets cover most elements of the periodic table past Kr. The most recent extension to the family has been for the elements Rb-Xe (JCC, 2020, 41, 1842), which includes very high quality yet still compact basis sets for the 4d elements. The development of the SARC basis sets had began with the third-row transition metals (5d series, Hf–Hg, JCTC, 2008, 4, 908 and JCTC, 2008, 4, 1449), and subsequently extended to the lanthanides (4f series, La–Lu, JCTC, 2009, 5, 2229), the actinides (5f series, Ac–Lr, JCTC, 2011, 7, 677), and the 6p elements (Tl–Rn, TCA, 2012, 131, 1292).

For calculations on lanthanides we have created a revised, larger, and more heavily polarized version called "SARC2" (JCTC, 2016, 12, 1148). The SARC2 improve specifically on the calculation of spectroscopic properties and are highly recommended for correlated single- or multi-reference wavefunction based calculations.

Further developments in our group focus on extensions to additional elements, on adaptation of the core region for finite-nucleus calculations, optimizations for prediction of core properties, and new complete versions for other popular relativistic Hamiltonians.