Complete basis set limit ionization potentials of O3 and NO2 using the multiconfigurational spin tensor electron propagator method (MCSTEP)

Excited and ionized states of ozone studied by the MEG (multi-exponentially generated)/EX (excited)-MEG method

“…With regard to the first three intense peaks at 12.7, 13.0, and 13.5 eV, there are many theoretical [4,6,9,[19][20][21][22][23][24][25][26][27] and experimental [12][13][14][15][16][17][18] studies. From the Koopmans' theorem, these three peaks are assigned to 1 2 A 2 , 1 2 A 1 , and 1 2 B 2 states, respectively.…”

“…Hartree-Fock (HF) single determinant becomes inadequate approximation due to the quasidegenerate electronic structure. Therefore, ozone has been a benchmark molecule [4][5][6][7][8][9][10][11] in the methodological developments of the multi-reference type theories in modern quantum chemistry.…”

“…Ionization spectra of ozone have also been extensively studied both by experiments [12][13][14][15][16][17][18] and theories [4,6,9,[19][20][21][22][23][24][25][26][27]. The quasi-degeneracy in the ground state causes a breakdown of the Koopmans' picture.…”

“…Therefore, multireference theories are required for accurate descriptions of the ionized states. For example, a problem in the assignment of the first three peaks had been discussed for many years but seems to have been settled recently [4,6,9,15,22]. However, only qualitative assignments [14,19,20] were given for many correlation peaks that were observed in the higherenergy region of the He II photoelectron spectrum [15].…”

Optical Potentials and Propagators for Elastic and Inelastic Scattering from Many-Body Targets

“…Feshbach resonances in the electron-helium scattering cross-section have been studied using a multichannel theory based on Green's functions [38]. Not connected to the subject of scattering, but certainly worth mentioning, is the successful work on Green's functions defined with respect to excited states of atoms [39,40].…”