The full-core plus correlation method with multi-configuration interaction wave functions is extended to the calcu-lation of the non-relativistic energies of 1s 2 n d (n ≤ 9) states for the lithium isoelectronic sequence from Z=11 to 20.Relativistic and mass-polarization effects on the energy are calculated as the first-order perturbation correction.The quantum-electrodynamics correction is also included.The fine structure splittings are determined from the expectation values of spin-orbit and spin-other-orbit interaction operators in the Pauli-Breit approximation.Combining the term energies of lowly excited states obtained with the quantum defects calculated by the single channel quantum defect theory,each of which is a smooth function of energy and approximated by a weakly varying function of energy,the ion potentials of highly excited states (n ≥ 6) are obtained with the semi-empirical iteration method.The results are compared with experimental data in the literature and found to be closely consistent with the regularity.
By using the full-core plus correlation (FCPC) type wave functions, the accurate charge densities ρ(0) at the nucleus and the radial expectation values of the ground states for the lithium-like systems with Z = 21 to 30 are obtained. The determinantal conditions and the electron-nucleus cusp condition are used to calculate the inequalities of the upper and the lower bounds to ρ(0) with two or more expectation values. These inequalities, derived by Angulo and Dehesa [Phys. Rev. A 44 1516 (1991)], are verified to be also valid for these ions with higher nuclear charge. The present results show that the wave functions used in this paper are satisfactory in the whole configuration space for these ions with higher nuclear charge.
