The generalized oscillator strengths for Na: monopole, dipole and quadrupole transitions

The generalized oscillator strengths (GOSs) of Na from the ground state [2p(6)3s] 3 (2)S excited to [2p(6)(n + 1)s](n + 1) (2)S, [2p(6)np]n (2)P, [2p(6)nd]n (2)D(3 <= n <= infinity) and adjacent continuum states are systematically investigated by the R-matrix method within the first Born approximation. The calculated energy levels of Na(+) and Na are in good agreement with the experimental values. The energy dependence of the GOS extrema for the monopole, dipole and quadrupole transitions is investigated. The GOS density surfaces of (2)S, (2)P and (2)D channels are calculated and their accuracies are tested rigorously by the available experiments as well as by the comparisons between the calculations on the different bases and the sum rule. With the surfaces tested, the high-energy electron impact excitation cross sections of the infinite Rydberg states near the threshold can be readily obtained by interpolations. In addition, the GOSDs for the resonance transitions 2p(6)3s -> 2p(5)3s(2) and 2p(6)3s -> 2p(5)3s3p are investigated.