@article {3503,
	title = {Momentum Profiles for Open-Shell Molecules: Studies of the HOMO{\textquoteright}s of NO, O<sub>2</sub>, and NO<sub>2</sub> by Electron Momentum Spectroscopy and SCF, Post-Hartree-Fock and DFT Calculations},
	journal = {Chem. Phys.},
	volume = {201},
	number = {1},
	year = {1995},
	note = {ISI Document Delivery No.: TH205Times Cited: 29Cited Reference Count: 74},
	month = {Dec},
	pages = {1-21},
	type = {Article},
	abstract = {<p>Measurements of the outermost valence electron orbital momentum profiles of the open shell molecules NO, O-2 and NO2 have been obtained using electron momentum spectroscopy (EMS). The presently reported experimental momentum profiles of NO and O-2 display much improved statistics compared with previously published EMS results while the data for the HOMO of NO, is the first reported. In the case of NO, the present measurements are considerably different from previous results and these differences appear to be due to the presence of NO2 impurities in the previous work. The EMS measurements provide a stringent test of basis set effects and the quality of ab initio methods in the description of these open shell systems. The experimental momentum profiles have been compared with theoretical spherically averaged momentum profiles from several basis sets calculated at the level of the target Hartree-Fock approximation (THFA) with a range of basis sets using both unrestricted Hartree-Fock (UHF) and restricted open shell Hartree-Fock (ROHF) methods. Various configuration interaction calculations such as multi-reference singles and doubles configuration interaction (MRSD-CI), averaged coupled pair functional (ACPF) and quasi-degenerate variational perturbation theory (QDVPT) calculations of the full ion-neutral overlap amplitude have also been compared to experiment to investigate the effects of electron correlation and relaxation. The experimental momentum profiles have further been compared to calculations at the level of the target Kohn-Sham approximation (TKSA) using density functional theory (DFT) with the local density approximation and also with gradient corrected exchange-correlation potentials. In addition to momentum profiles, other electronic properties such as total energies, dipole moments, quadrupole moments and values of the electronic spatial extent have been calculated by the various theoretical methods and compared to experimental values.</p>},
	keywords = {CORRELATED WAVEFUNCTIONS, CORRELATION ENERGIES, density, DIPOLE-MOMENT, EXCHANGE-ENERGY, GAUSSIAN-BASIS SETS, NITRIC-OXIDE, VALENCE ORBITALS, VARIATIONAL PERTURBATION-THEORY, WAVE-FUNCTIONS},
	isbn = {0301-0104},
	url = {<Go to ISI>://A1995TH20500001},
	author = {Rolke, J. and Cann, N. and Zheng, Y. and Hollebone, B. P. and C. E. Brion* and Wang, Y. A. and Davidson, E. R.}
}
@article {6980,
	title = {QUASI-PARTICLE EQUATION FROM THE CONFIGURATION-INTERACTION (CI) WAVE-FUNCTION METHOD},
	journal = {International Journal of Quantum Chemistry},
	volume = {40},
	number = {2},
	year = {1991},
	note = {ISI Document Delivery No.: FX545Times Cited: 7Cited Reference Count: 42},
	month = {Aug},
	pages = {225-242},
	type = {Article},
	abstract = {The Green-function method is a well-known way to reduce the quantum mechanical problem of n electrons moving in the field of clamped nuclei to the problem of solving a one-electron Schrodinger equation (the quasi-particle equation) involving a pseudopotential (the self-energy). This method is widely used in solid-state, low-energy electron-molecule scattering, ionization, and electron attachment theory, and much work has focused on finding accurate self-energy approximations. Unfortunately, the operator nature of the fundamental quantity (Green function) in the usual quasi-particle equation formalism significantly complicates the derivation of self-energy approximations, in turn significantly complicating applications to inelastic scattering and multiconfigurational bound-state problems. For these problems or wherever the operator approach becomes inconvenient, we propose an alternative quasi-particle equation derived wholely within a configuration interaction wave-function formalism and intended to describe the same phenomenology as does the Green function quasi-particle equation. Our derivation refers specifically to electron removal but is readily generalized to electron attachment and scattering. Although the Green function and wave-function quasi-particle equations are different, we emphasize the parallels by rederiving both equations within the equations-of-motion formalism and then producing a wave-function analog of the Green function two-particle-hole Tamm-Dancoff approximation.},
	keywords = {APPROXIMATION, CLOSED-SHELL ATOMS, CORRELATED WAVEFUNCTIONS, ELECTRON PROPAGATOR THEORY, ENERGIES, EXTENSION, IONIZATION-POTENTIALS, KOOPMANS THEOREM, MOLECULES, SCATTERING},
	isbn = {0020-7608},
	url = {<Go to ISI>://A1991FX54500005},
	author = {Casida, M. E. and Chong, D. P.}
}
