The extended Koopmans’ theorem: Vertical ionization potentials from natural orbital functional theory

2012 ◽  
Vol 136 (17) ◽  
pp. 174116 ◽  
Author(s):  
Mario Piris ◽  
Jon M. Matxain ◽  
Xabier Lopez ◽  
Jesus M. Ugalde
Keyword(s):  
Ionization Potentials ◽  
Natural Orbital ◽  
Functional Theory ◽  
Koopmans Theorem ◽  
Vertical Ionization Potentials ◽  
Natural Orbital Functional Theory

Prediction of the photoelectron spectrum for XPY2 (X = H, F, Cl; Y = O, S) type of molecules by ab initio and DFT methods

2006 ◽  
Vol 84 (1) ◽  
pp. 5-9 ◽  
Author(s):  
Didier Bégué ◽  
Jean-marc Sotiropoulos ◽  
Claude Pouchan ◽  
Daisy Y Zhang
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Radical Cations ◽  
Dft Methods ◽  
Functional Theory ◽  
Hartree Fock ◽  
Orbital Energies ◽  
Koopmans Theorem ◽  
Vertical Ionization Potentials ◽  
Hybrid Density Functional

The present study reports the theoretical vertical ionization potentials (IPs) for all the valence electrons in six XPY2 molecules by utilizing the corrected orbital energies calculated with three theoretical methods, namely, the ab initio Hartree–Fock (HF), and both the pure and hybrid density functional theory (DFT) methods at, respectively, the BLYP/6-311+G* and B3lYP/6-311+G* levels of theory. Evaluation of the numerical corrections to the orbital energies was achieved by comparisons with the IP values obtained via explicit computation of the energy differences between the neutral molecules and the corresponding radical cations (the ΔSCF method) and shows values from –0.9 to –1.9 eV for the HF, and positive values from 2.9 to 3.9 eV and from 1.8 to 2.4 eV for the pure and hybrid DFT methods, respectively. In contrast to the orbital energies, the ΔSCF method is shown to give consistent values among the three methods, as well as reasonable agreement with the experimental IP values.Key words: ionization potential, phosphorane, Koopmans' theorem, Janak's theorem.

Natural Orbital Functional Theory and Reactivity Studies of Diradical Rearrangements: Ethylene Torsion as a Case Study

ChemPhysChem ◽  
2011 ◽  
Vol 12 (9) ◽  
pp. 1673-1676 ◽  
Author(s):  
Xabier Lopez ◽  
Mario Piris ◽  
Jon M. Matxain ◽  
Fernando Ruipérez ◽  
Jesus M. Ugalde
Keyword(s):  
Natural Orbital ◽  
Functional Theory ◽  
Natural Orbital Functional Theory

Homolytic molecular dissociation in natural orbital functional theory

2011 ◽  
Vol 13 (45) ◽  
pp. 20129 ◽  
Author(s):  
J. M. Matxain ◽  
M. Piris ◽  
F. Ruipérez ◽  
X. Lopez ◽  
J. M. Ugalde
Keyword(s):  
Natural Orbital ◽  
Molecular Dissociation ◽  
Functional Theory ◽  
Natural Orbital Functional Theory
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