@article {2591,
	title = {An evaluation of exchange-correlation functionals for the calculations of the ionization energies for atoms and molecules},
	journal = {Journal of Electron Spectroscopy and Related Phenomena},
	volume = {171},
	number = {1-3},
	year = {2009},
	note = {ISI Document Delivery No.: 452BQTimes Cited: 6Cited Reference Count: 82Segala, Maximiliano Chong, Delano P.},
	month = {Apr},
	pages = {18-23},
	type = {Article},
	abstract = {In this paper, ionization energies of gas-phase atoms and molecules are calculated by energy-difference method and by approximate transition-state models with density functional theory (DFT). To determine the best functionals for ionization energies, we first study the H to Ar atoms. An approximation is used in which the electron density is first obtained from Kohn-Sham computations with an exchange-correlation potential V-xc known as statistical average of orbital potentials (SAOP), after which the energy is computed from that density with 59 different exchange-correlation energy functionals E-xc. For the 18 atoms, the best E-xc functional providing an average absolute deviation (AAD) of only 0.110 eV is one known as the Krieger-Chen-lafrate-Savin functional modified by Krieger, Chen, Iafrate, and Kurth, if one uses the spin-polarized spherical atom description. On the other hand, if one imposes the condition of integer-electrons, the best functional is the Becke 1997 functional modified by Wilson, Bradley, and Tozer, with an AAD of 0.107 eV, while several other functionals perform almost as well. For molecules, we can achieve an accuracy of AAD = 0.21 eV for valence VIPs of nonperhalo molecules with Delta E(V-xc = SAOP;PBEO) using integer-electron description. For perhalo molecules our best approach is Delta E(V-xc from either E-xc or SAOP;mPW1PW) with full symmetry to obtain an AAD = 0.24 eV. (c) 2009 Elsevier B.V. All rights reserved.},
	keywords = {ADJUSTABLE-PARAMETERS, ASYMPTOTIC-BEHAVIOR, DFT, Energy-difference method, EXCITATION-ENERGIES, GENERALIZED GRADIENT APPROXIMATION, HE(II) PHOTOELECTRON-SPECTRA, Integer-electron, Ionization energy, models, ORBITAL MODEL POTENTIALS, ORGANIC-MOLECULES, PHOTO-ELECTRON SPECTRA, Slater-type orbitals, Spin-polarized spherical atom, STATISTICAL AVERAGE, TRANSITION-STATE},
	isbn = {0368-2048},
	url = {<Go to ISI>://000266515000002},
	author = {Segala, M. and Chong, D. P.}
}
@article {5195,
	title = {PW86-PW91 density functional calculation of vertical ionization potentials: Some implications for present-day functionals},
	journal = {International Journal of Quantum Chemistry},
	volume = {81},
	number = {1},
	year = {2001},
	note = {ISI Document Delivery No.: 380EFTimes Cited: 14Cited Reference Count: 50},
	month = {Jan},
	pages = {34-52},
	type = {Article},
	abstract = {A total of 181 vertical ionization potentials (VIPs) of 41 molecules were calculated by density functional theory (DFT) employing the Perdew-Wang 1986 (PW86) exchange and Perdew-Wang 1991 (PW91) correlation functionals and using the aug-cc-pV5Z basis and experimental ground-state geometries. The overall average absolute deviation (AAD) from experiment was found to be 0.55 eV and only 0.31 eV for linear molecules but 0.86 eV for nonplanar molecules. A number of VIPs were in error by over 2 eV. In particular, DFT performed most poorly when ionization was from an orbital with highly varying density gradients (which arise from the orbital{\textquoteright}s shape or compactness or through its density being distributed over a number of atoms). Indications are that many or all present-day functionals suffer from the same failings. (C) 2001 John Wiley \& Sons, Inc.},
	keywords = {ACCURATE, AROMATIC MOLECULES, CORRELATED MOLECULAR CALCULATIONS, DFT, EXCHANGE-ENERGY, functionals, GAUSSIAN-BASIS SETS, HE(II) PHOTOELECTRON-SPECTRA, ionization potential, ORGANIC-MOLECULES, PHOTO-ELECTRON SPECTRA, PW86, PW91, SPECTROSCOPY, WAVE-FUNCTIONS},
	isbn = {0020-7608},
	url = {<Go to ISI>://000165685400007},
	author = {Shapley, W. A. and Chong, D. P.}
}
