Lower Rydberg ² F states of the lithium atom: Finite-nuclear-mass calculations with explicitly correlated Gaussian functions

Variational non-relativistic calculations are performed for the four lowest Rydberg ²F states (1s²nf, n = 4,., 7) of the main isotope of the lithium atom (⁷Li). 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. A total of 140 Gaussians are used for each state. The calculated relative energy of the two lowest states is compared with the experimental value, which is the only value available in the literature. The two results agree within a few wavenumbers.