RHF-DFT approach for electron affinities of neutral atoms in groups 13 and 14

Abstract

The pseudo-relativistic Hartree-Fock and density functional theory (DFT) has been used to calculate electron affinities of neutral atoms of the group-13 elements (B-, Al-, Ga-, In- and Tl-) and the group-14 elements (C-, Si-, Ge-, Sn- and Pb-). A simple approximate correlation-correction potential term derived from the DFT was added to the usual single-particle pseudo-relativistic Hartree-Fock Hamiltonian. In carrying out the calculations a novel scheme has been devised to obtain appropriate scaling factors for the Coulomb radial integrals of the group-14 elements. These same factors can be transportable without adjustment to the group-13 elements, on the basis of their similar electron pair correlation energies. The validity of our results is amply demonstrated by the consistency between our computed electron affinities and existing data. For the first four elements of group 13, our values are in good agreement with both the recent multi-configuration Dirac-Fock (MCDF) and the relativistic coupled-cluster (RCC) values. The electron affinity of 0.388 eV for the fifth element, Tl-, obtained in the present calculation is in better agreement with the RCC value (0.40 ± 0.05 eV) than the MCDF value (0.291 eV).