Theoretical fine spectroscopy with symmetry adapted cluster–configuration interaction general-$R$ method: First-row $K$-shell ionizations and their satellites

Molecular core ionization spectra and their satellites were studied by the symmetry adapted cluster–configuration interaction (SAC-CI) general-$R$ method. The core-electron binding energies of C, N, O, and F atoms of 22 molecules were calculated with an average deviation of 0.11 eV from the experimental values. The energy splittings between $K$-shell gerade and ungerade states were calculated and discussed in relation to the bond length. The satellite spectra of the C 1s and N 1s core ionizations of methane and ammonia were investigated. The SAC-CI general-$R$ method gave many shake-up states with moderate intensities, reproducing the general feature of the experimental spectra, and thus enabling the detailed understanding and assignments of the core-electron ionization spectra.