Ground and excited states of Li −, Be − through a density-based approach

Abstract

Density functional theory (DFT)-based calculations are performed for ground [He]2s 2 1S e, and three metastable bound excited states, 1s2s2p 2 5P e, 1s2p 3 5S o, 1s2s2p3p 5P e of Li − and [He]2s2p 2 4P e, [He]2p 3 4S o, 1s2s2p 3 6S o of Be − each. The Kohn–Sham equation is solved by generalized pseudospectral method using the work-function-based exchange and Lee–Yang–Parr correlation potential. Total energies ( E), radial densities, selected density moments and two transition wavelengths ( λ) (1s2s2p 2 5P e → 1s2p 3 5S o of Li −, [He]2s2p 2 4P e → [He]2p 3 4S o of Be −) show reasonably good agreement with available theoretical and experimental data. Absolute deviations in E are within 0.007–0.171%, while λ of Li − and Be − deviate by 0.891% and 0.438% of the experimental values. This offers a simple practical route towards accurate reliable calculation of excited states of anions within DFT.