Inner-shell excitations of water molecule Original Research Article

Theoretical results for the generalized oscillator strength (GOS) and optical oscillator strength (OOS) have been obtained for the excitations from the ground state X1Σ+ to the inner-shell (O1s) 1A1(1a1→4a1), 1B2(1a1→2b2), 1B1(1a1→2b1) electronic states within the first Born approximation (FBA). The target electronic wave functions were determined using the configuration-interaction method, with a Hartree-Fock basis for the occupied molecular orbitals, and improved virtual orbitals for the virtual space. Relaxation and correlation effects were explicitly taken into account. We present, as well, results for the generalized oscillator strength of the first valence A1B1 excited state, in connection with the discussion of the inner-shell problem. The results were compared with the available experimental and theoretical data.