Electron-Impact Excitation of 51S – 51Po Resonance Transition in Sr Atom

Main aspects of a new version of the B-spline R-matrix (BSR) method, in which nonorthogonal orbitals are applied, have been described. The BSR approximation is used to calculate the resonance structure of integral cross-sections of the 51S - 51Po transition at the electron scattering by a strontium atom in the energy interval up to 10 eV. The multiconfiguration Hartree–Fock method with a nonorthogonal set of orbitals is employed to accurately represent the target wave functions. The close-coupling expansion included 31 bound states of a neutral strontium atom ranging from the ground state to the 5s5f 1Fo one. The calculated cross-sections are in good agreement with available experimental data and can be exhaustively interpreted. The structure of a resonance feature in the e-Sr scattering cross-sections at about 4 eV is discussed.