Generalized oscillator strengths for dipole and octupole 3p → (3d, 4d, 5d), quadrupole and hexadecapole 3p → 4f transitions of argon atomic in the length and velocity formulations

The generalized oscillator strengths (GOS) of the argon transitions 3p6−3p5(3d, 4d, 5d) and 3p6−3p54f respectively for multiple strengths and are determined using the wavefunctions which have been generated from the CIV3 code of Hibbert. Calculations of these generalized oscillator strengths, as a function of momentum transfer, are also carried out respectively in the configuration interaction method and in the random phase approximation with exchange. The length and velocity forms have been used in this work. The gap between the absolute values of the generalized oscillator strength obtained in the theoretical calculations and those of the experimental results of Zhu et al have been noticeably reduced in the present work for the octupole excitations to 3p5(3d, 4d). This is due to the configuration interaction wavefunctions. The profiles and the positions of the extrema in the generalized oscillator strength have also received particular attention in the evaluation. The results of length and velocity form studies also show that the electron correlation effects are very significant for the excitations to 3p5(3d, 4d) but are found to have no great influence in the positions of the extrema.