Ionization potential for excitedSstates of the lithium atom

Uncertainty estimates for theoretical atomic and molecular data

“…For the two-and three-electron cases of helium-like and lithium-like atoms complete calculations in Hylleraas coordinates have been performed. Recent high-precision measurements [173,174] and theory [175][176][177] for the 1s 2 2s 2 S − 1s 2 3s 2 S two-photon transition in lithium provide an excellent example of what can be achieved. Table I lists the various contributions to the transition frequency, expressed as a double power series in powers of µ/M and α, where µ/M is the ratio of the reduced electron mass to the nuclear mass, and α is the fine structure constant (see table caption for numerical values).…”

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

“…[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.…”

“…The calculations, which involve generating an ECG basis for each studied state, are first performed for the most abundant lithium isotope, 7 Li. Subsequently, the basis sets generated for the nine 2 P o states of 7 Li are used in the calculations for 6 Li, as well as in the calculations of the lithium atom with an infinite nuclear mass ( ∞ Li).…”

“…The calculations, which involve generating an ECG basis for each studied state, are first performed for the most abundant lithium isotope, 7 Li. Subsequently, the basis sets generated for the nine 2 P o states of 7 Li are used in the calculations for 6 Li, as well as in the calculations of the lithium atom with an infinite nuclear mass ( ∞ Li). The purpose of the latter set of calculations is to generate energies that can be directly compared with the results obtained in conventional nonrelativistic calculations, which are usually performed with the infinite-nuclear-mass approach (i.e., by assuming the Born-Oppenheimer approximation).…”

Assessment of the accuracy the experimental energies of the 1P o 1s22s6p and 1s22s7p states of 9Be based on variational calculations with explicitly correlated Gaussians

“…For two-and three-electron atomic systems, such as the helium and lithium atoms, the explicitly correlated Hylleraas-type basis functions have provided the highest accuracy level in the calculations. [3][4][5][6] The wave functions constructed from Hylleraas-type functions can satisfy the Kato cusp conditions, 7 which is a desirable feature in very accurate calculations. Unfortunately, the applicability of Hylleraas-type basis functions is limited to atoms with no more than three electrons due to unresolved issues in calculating the Hamiltonian matrix elements (at least for the general form of the basis functions).…”