Relativistic R-matrix close-coupling method based on the effective many-body Hamiltonian: electron-impact excitation of electric dipole-allowed and spin-forbidden transitions of the S4+ ion

Electron-impact excitation cross sections of the electric dipole-allowed 3s(2) S-1(0) -> 3s3p P-1(1)o and spin-forbidden 3s(2) S-1(0) -> 3s3p P-3(0,1,2)o transitions in Mg-like sulfur (S4+) are calculated using the effective many-body Hamiltonian R-matrix close-coupling method. The calculated near-threshold electron-impact excitation cross sections for the electric dipole-allowed 3s(2) S-1(0) -> 3s3p P-1(0)o transitions are in good agreement with experimental results. The electron-impact excitation cross sections for the spin-forbidden 3s(2) S-1(0) -> 3s3p P-3(0,1,2)o transitions have been computed to benchmark theoretical accuracy against future experimental studies.