Density functional calculations on triply excited states of lithium isoelectronic sequence

Abstract

Triply excited states of many-electron atomic systems are characterized by the presence of strong electron correlation, closeness to more than one threshold, and degeneracy with many continua; therefore, they offer unusual challenges to theoretical methodologies. In the present article, we computed with reasonable accuracy all the n=2 intrashell triply excited states (2s²2p ²P 2s2p^{2 2}D, ⁴P, ²P, ²S; and 2p^{3 2}D, ²P, ⁴S) of three-electron atomic systems (Z=2,3,4,6,8,10) by using a density functional formalism developed recently in our laboratory, based on the nonvariational Harbola-Sahni exchange potential in conjunction with a parametrized local Wigner and Lee-Yang-Parr correlation potentials. Nonrelativistic energies and densities are obtained by solving a Kohn-Sham-type differential equation. The calculated results are compared with available experimental and other theoretical data. The 2p³(⁴S)→1s2p²(⁴P) transition wavelength for the isoelectronic series is also computed. The overall good agreement of our results with the literature data indicates the reliability of the present density functional methodology for excited states of many-electron systems.