# Finite-element multiconfiguration Hartreeâ€“Fock calculations on the excitation energies and the ionization potential of oxygen

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- Calculation and interpretation of total energies in electron propagator theory. Ortiz, J. V. // Journal of Chemical Physics;10/1/1995, Vol. 103 Issue 13, p5630
Ground state total energies and one-electron density matrices can be calculated from contour integrals over the electron propagator. Ionization energies and corresponding Feynmanâ€“Dyson amplitudes are related simply to ground state properties. Total energy formulas derived from electron...

- Comparison between molecular orbital and surface integral calculations of the exchange energy for the homonuclear dimer ions He+2, Li+2, and Be+2. Chang, T. C.; Tang, K. T. // Journal of Chemical Physics;12/22/1995, Vol. 103 Issue 24, p10580
The exchange energy, defined as half of the energy splitting of the gerade and ungerade states of a molecular ion, is investigated by molecular orbital calculations and by the surface integral method. Numerical results of He+2, Li+2, and Be+2 are obtained through restricted Hartreeâ€“Fock,...

- Radial behavior of the average local ionization energies of atoms. Politzer, Peter; Murray, Jane S.; Grice, M. Edward; Brinck, Tore; Ranganathan, Shoba // Journal of Chemical Physics;11/1/1991, Vol. 95 Issue 9, p6699
The radial behavior of the average local ionization energy I(r) has been investigated for the atoms Heâ€“Kr, using ab initio Hartreeâ€“Fock atomic wave functions. I(r) is found to decrease in a stepwise manner with the inflection points serving effectively to define boundaries between...

- The exactness of the extended Koopmansâ€™ theorem: A numerical study. Sundholm, Dage; Olsen, Jeppe // Journal of Chemical Physics;3/1/1993, Vol. 98 Issue 5, p3999
The exactness of the extended Koopmansâ€™ theorem has been studied by comparing multiconfiguration Hartreeâ€“Fock calculations on Be(1S) with configuration interaction calculations on Be+(2S) performed in the same basis. The lowest ionization potentials calculated as the energy...

- A linear combination of Gaussian-type orbitals (LCGTO) XÎ± study of ferrocene: The metal-to-ring distance and ionization potentials. Rösch, N.; Jörg, H. // Journal of Chemical Physics;5/15/1986, Vol. 84 Issue 10, p5967
The metal-to-ring distance of ferrocene, Fe(C5H5)2, has been optimized using the LCGTO-XÎ± method. The resulting distance is 0.047 Ã… shorter than the experimental value of 1.65 Ã…. The corresponding symmetric stretching frequency of 331 cm-1 shows good agreement with experiment (303...

- Relativistic effects on sixth group monohydrides. Pisani, L.; Clementi, E. // Journal of Chemical Physics;12/1/1995, Vol. 103 Issue 21, p9321
Diracâ€“Fock and Hartreeâ€“Fock calculations have been performed for the ground state of the HO, HS, HSe, HTe, and HPo molecules. Equilibrium geometries, atomization energies, and ionization potentials, with both methods, are evaluated, compared, and discussed. Calculations on the...

- Exact ionization potentials from wavefunction asymptotics: The extended Koopmansâ€™ theorem, revisited. Vanfleteren, Diederik; Van Neck, Dimitri; Ayers, Paul W.; Morrison, Robert C.; Bultinck, Patrick // Journal of Chemical Physics;5/21/2009, Vol. 130 Issue 19, p194104
A simple explanation is given for the exactness of the extended Koopmansâ€™ theorem, (EKT) for computing the removal energy of any many-electron system to the lowest-energy ground state ion of a given symmetry. In particular, by removing the electron from a â€œremoval orbitalâ€ of...

- Stability of MX2-3 ions in the gas phase and when do ionic molecules have large ionization potentials. Scheller, M. K.; Cederbaum, L. S. // Journal of Chemical Physics;7/1/1993, Vol. 99 Issue 1, p441
The present work aims at theoretical consideration of the geometrical and electronic structures of a homologous series of free MXmq--type alkali halides (M=Li, Na, K; X=F, Cl; m=1,2,3; q=0,1,2) in order to get insight into their kinetic and electronic stability. At the ab initio...

- The S1/S2 exciton interaction in 2-pyridoneÂ·6-methyl-2-pyridone: Davydov splitting, vibronic coupling, and vibronic quenching. Heid, Cornelia G.; Ottiger, Philipp; Leist, Roman; Leutwyler, Samuel // Journal of Chemical Physics;10/21/2011, Vol. 135 Issue 15, p154311
The excitonic splitting between the S1 and S2 electronic states of the doubly hydrogen-bonded dimer 2-pyridoneÂ·6-methyl-2-pyridone (2PYÂ·6M2PY) is studied in a supersonic jet, applying two-color resonant two-photon ionization (2C-R2PI), UV-UV depletion, and dispersed fluorescence...