Performance of Relativistic Effective Core Potentials for Closed‐Shell Superheavy Element Halides in DFT and TDDFT Calculations

The accuracy of pseudopotentials (PPs) in density functional theory (DFT) and time‐dependent DFT (TDDFT) calculations has been studied previously. However, the performance of PPs including spin‐orbit coupling (SOC) for superheavy element compounds where SOC is very strong was rarely investigated. In this work, we report the performance of the small‐core energy‐consistent PPs developed by Stuttgart groups on the ground state bond lengths, force constants, dissociation energies in DFT calculations and on vertical excitation energies in TDDFT calculations for a series of closed‐shell superheavy element halides, compared with results obtained using all‐electron Dirac‐Coulomb(‐Gaunt) Hamiltonian. In most cases, results with the PPs are in good agreement with all‐electron results in scalar relativistic and SOC calculations. PP deviations are insensitive to the employed exchange‐correlation functionals in most cases. Effects of the basis set on these properties in PP calculations are very small. Our results indicate that reasonable DFT and TDDFT results can be given by such PPs for these superheavy elements halides.