Electron-impact excitation of the Mg atom from the ground and metastable states: R-matrix calculation with pseudostates

The recently developed R-matrix method with pseudostates (in a 19-state clo se-coupling approximation) has been applied in the calculation of integral cross sections for electron-impact excitation of neutral Mg. A configuratio n interaction representation with frozen core is used for the outer electro ns. Results are presented for transitions from both the (3s(2))S-1 ground s tate and the (3s3p)P-3 metastable state to the 13 lowest-excited target sta tes (with principal quantum numbers n = 3,4,5), as well as elastic cross se ctions, incident electron energies range from threshold to 30 eV. Interpret ations are given, with emphasis on comparison of absolute values of the the oretical and measured cross sections and their energy dependence in the nea r-threshold-region. [S1050-2947(99)04603-X].