Nagy E. Inclusion of electron correlation in the electron scattering on complex atoms within the B-spline R-matrix method framework

With the use of term-dependent non-orthogonal orbitals and B-splines as basis functions, an extended version of the BSR R-matrix method, which provides an effective treatment of electron correlation, has been proposed and implemented. Systematic calculations of the energy and angular dependences of the integral (ICS) and differential (DСS) cross sections have been carried out for the elastic scattering, excitation and ionization of atoms of magnesium, strontium, silicon and fluorine by electron impact. The results show good agreement with a large amount of experimental data in the wide range of collision energies. The effect of coupling between the discrete states and the continuum have been scrutinized for the excitation and ionization of atoms by electron impact and the necessity of taking them into account in calculations of the scattering characteristics in the e-Si and e-F problems has been demonstrated. Strong sensitivity of the scattering cross sections to the electron correlation both in the N-electron atomic target and in the (N + 1)-electron collision system has been revealed. It is shown that inclusion of the valence and core-valence electron correlation through the mixing of the ground state configuration of the target atom with additional configurations with the excited core significantly improves the agreement between the calculated ICS and DСS and the experimental data. Overall, 24 Feshbach-type resonances have been revealed in the scattering of electrons by F atom, with their parameters (position and width) have been determined and their spectroscopic classification has been established.