Lower Rydberg2Dstates of the lithium atom: Finite-nuclear-mass calculations with explicitly correlated Gaussian functions

Abstract

Very accurate variational nonrelativistic calculations are performed for the five lowest Rydberg 2 D states (1s 2 nd 1 , n = 3, . . . ,7) of the lithium atom ( 7 Li). The finite-nuclear-mass approach is employed and the wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian function. Four thousand Gaussians are used for each state. The calculated relative energies of the states determined with respect to the 2 S 1s 2 2s 1 ground state are systematically lower than the experimental values by about 2.5 cm −1 . As this value is about the same as the difference between the experimental relative energy between 7 Li + and 7 Li in their ground-state energy and the corresponding calculated nonrelativistic relative energy, we attribute it to the relativistic effects not included in the present calculations.

1Dstates of the beryllium atom: Quantum mechanical nonrelativistic calculations employing explicitly correlated Gaussian functions

“…We recently investigated the Rydberg series of 2 D states of the lithium atom in very accurate quantum-mechanical calculations carried out with explicitly correlated Gaussian functions [1,2]. A total of nine states were computed.…”

Theory and application of explicitly correlated Gaussians

“…They include the low-lying excited states and encompass states with nonzero angular momentum Stanke et al, 2007b;Stanke, Komasa et al, 2009;Sharkey, Bubin, and Adamowicz, 2011b).…”

Explicitly correlated Gaussian calculations of the 2P o Rydberg spectrum of the lithium atom

“…A good example here is the lithium atom, for which the Gaussian calculations provided the most accurate available transition energies of 2 D Rydberg states. 11,12 This may be associated with the higher flexibility of Gaussians in describing rich nodal structures of excitedstate wave functions. However, it may also be because the use of Hylleraas functions in high-accuracy calculations of states with higher angular and radially excitations has not yet been scrutinized.…”

“…[1][2][3][4][5][6][7][8][9] We have also contributed to this effort. [10][11][12] 13 basis functions because they are capable of very well describing the medium and long range electron correlations. They also have the correct behavior at short electronelectron and electron-nucleus distances.…”