On the transferability of relativistic pseudopotentials in density-functional calculations: AuH, AuCl, and Au ₂

The ground-state R_e, ω_e, and D_e of Au₂ are calculated using non-relativistic and scalar relativistic pseudopotentials (PP), which are compared with all-electron non-relativistic and Douglas-Kroll-Hess results, respectively, at ab initio and density-functional levels of theory. The correlation effects of electrons defined as a core part in the 'small-core' PPs are found be very small in both non-relativistic and relativistic all-electron calculations. The 'small-core' relativistic PPs can be used in density-functional calculations with little loss of accuracy, as well as non-relativistic PPs, for the ground states of AuH, AuCl, and Au₂.