Electron affinity of lead: An ab initio four-component relativistic study

The electron affinity of lead is calculated to be 0.403 eV, using four-component relativistic multiconfigurational quasidegenerate perturbation theory. Uncontracted (27s 23p 16d 10f 2g) Gaussian-type functions are used to generate valence basis functions (7s 9p− 10p+ 8d± 10f± 2g±) in the reduced frozen core approximation, where the KLM shells are frozen. The electrons in the remaining shells are correlated in the perturbation calculations with the (6s, 6p) complete active space. The calculated value is within 10% of the experimental value of 0.364 eV. The energy levels of the low-lying excited states of Pb and Pb− are also calculated.