Aspects of Electronic Configuration Interaction in Molecular Photoionization
Experimental studies have been reported recently of partial-channel photoionization cross sections in diatomic and polyatomic molecules1–3. Many of the measured cross sections can be understood and clarified quantitatively on basis of theoretical studies in the so-called separated-channel static-exchange approximation4. In this approach, Hartree-Fock functions are employed for the electronic portions of target ground states, and corresponding continuum molecular eigenfunctions are constructed in the orbital approximation employing non-central static-exchange potentials. Consequently, the calculated partial-channel cross sections so obtained refer simply to the separate removal of electrons from the individual molecular orbitals of a molecule, and they do not take into account the configuration mixing possible among the various ionization channels. There are important cases, however, in which the effects of electronic configuration interaction do not simply provide small corrections to separated-channel static-exchange results, but, rather, dominate the spectral characteristics of partial-channel cross sections5–7. In these cases it is generally necessary to include initial and final-state configuration-mixing effects, as well as scattering-function coupling, in theoretical studies of molecular partial-channel photoionization cross sections.
Unable to display preview. Download preview PDF.
- 2.G.V. Marr, Daresbury Rept. DL/SRF/P417 (1978).Google Scholar
- 3.CE. Brion and A. Hamnett, Advan. Chem. Phys. 45,2 1981.Google Scholar
- 11.Geoffry R.J. Williams and P.W. Langhoff, Chem. Phys. Letters 60, 201 (1978).Google Scholar
- 16.I.N. Levine, Quantum Chemistry (Allyn and Bacon, Boston, 1970), Vol.II.Google Scholar
- 25.I. Shavitt, “The Method of Configuration Interaction”, in: Methods of Electronic Structure Theory, ed. H. F. Schaefer III (Plenum, NY, 1977), Vol.3, Chap.6.Google Scholar
- 27.K. Siegbahn, C. Nordling, G. Johansson, J. Hedman, P.F. Heden, K. Hamrin, U. Gelius, T. Bergmark, L.O. Werme, R. Manne, and Y. Bauer, ESCA Applied to Free Molecules (North-Holl and, Amsterdam, 1969).Google Scholar
- 28.D.W. Turner, C. Baker, A.D. Baker, and C.R. Brundle, Molecular Photoelectron Spectroscopy (Wiley, New York, 1970).Google Scholar
- 30.T.A. Carlson, X-ray Photoelectron Spectroscopy (Academic, New York, 1978), Part III.Google Scholar
- 32.T.H. Dunning and J.P. Hay, in Modern Theoretical Chemistry, H.F. Schaefer III, Editor (Plenum, NY, 1976), Vol.3, Chap. 1.Google Scholar
- 33.H.F. Schaefer III, The Electronic Structure of Atoms and Molecules (Addison-Wesley, reading, MA, 1972).Google Scholar
- 34.P.W. Langhoff, “The Stieltjes-Tchebycheff Approach to Molecular Photoionization Studies,” in Electron-Molecule and Photon-Molecule Collisions, T.N. Rescigno, B.V. Mc koy, and B. Schnei-der, Editors (Plenum, N.Y., 1979), pp. 183-224.Google Scholar
- 35.P.W. Langhoff, “Stieltjes-Tchebycheff Moment-Theory Approach to Photoeffect Studies in Hubert Space”, in Theory and Application of Moment Methods in Many-Fermion Systems, B.J. Dalton, S.M. Grimes, J.P. Vary, and S.A. Williams, Editors (Plenum, NY, 1980), pp. 191-212.Google Scholar
- 38.R.S. Mulliken and W.C. Ermler, Diatomic Molecules (Academic, NY, 1977).Google Scholar