@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 {2392,
	title = {Theoretical study of the electronic spectra of s-triazine vapour},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {87},
	number = {8},
	year = {2009},
	note = {ISI Document Delivery No.: 493VQTimes Cited: 3Cited Reference Count: 37Chong, Delano P.},
	month = {Aug},
	pages = {1148-1153},
	type = {Article},
	abstract = {The ionization and excitation spectra of valence and core electrons of s-triazine in the gas phase are studied with ab initio, density functional, and semi-empirical methods. The results are compared with available experimental data and previous calculations. New estimates are proposed for the ionization energies of both valence and core electrons. The calculated excitation energies are consistent with experiment.},
	keywords = {AB-INITIO, AZINES, core-electron binding energies, DENSITY-FUNCTIONAL THEORY, DFT, electron spectra, ESCA, EXCHANGE-CORRELATION POTENTIALS, EXCITATION-ENERGIES, excitations, HYDROGEN, IONIZATION-POTENTIALS, ionizations, MOLECULAR CALCULATIONS, N-2, photoelectron spectra, s-triazine, SPECTROSCOPY, UV absorption},
	isbn = {0008-4042},
	url = {<Go to ISI>://000269766800008},
	author = {Chong, D. P.}
}
@article {2046,
	title = {Density functional theory calculation of 2p spectra of SiH4, PH3, H2S, HCl, and Ar},
	journal = {International Journal of Quantum Chemistry},
	volume = {108},
	number = {8},
	year = {2008},
	note = {ISI Document Delivery No.: 297FSTimes Cited: 0Cited Reference Count: 48Chong, Delano P. Segala, Maximiliano Takahata, Yuji Baerends, E. J.},
	month = {Jul},
	pages = {1358-1368},
	type = {Article},
	abstract = {The method developed recently for prediction of Is electron spectra is now extended to the 2p spectra of SiH4, PH3, H2S, HCl, and Ar. The method for X-ray absorption spectra involves the use of Delta E for the excitation and ionization energies, and application of time-dependent density functional theory using the exchange-correlation potential known as statistical average of orbital potentials for the intensities. Additional assumptions and approximations are also made. The best exchange-correlation functional E-xc for the earlier calculation of Delta E in Is spectra of C to Ne (namely Perdew-Wang 1986 exchange, combined with Perdew-Wang 1991 correlation) is no longer used in this work on 2p spectra of Si to Ar. Instead, recently tested Exc good for 2p core-electron binding energies (known as OPTX) for exchange and LYP for correlation, plus scalar zeroth-order regular approximation is adopted here for the Delta E calculations. Our calculated X-ray absorption spectra are generally in good agreement with experiment. Although the predictions for the higher excitations suffer from basis set difficulties, our procedure should be helpful in the interpretation of absorption spectra of 2p electrons of Si to Ar. In addition, we report calculated results for other kinds of electron spectra for SiH4, PH3, H2S, HCl, and Ar, including valence electron ionizations and excitations as well as X-ray emission. (C) 2008 Wiley Periodicals, Inc.},
	keywords = {2p spectra, ACCURATE, CORE, DFT, ELECTRON BINDING-ENERGIES, EXCHANGE-CORRELATION POTENTIALS, EXCITATION-ENERGIES, excitations, EXCITED-STATES, GAS, INNER, ionizations, MOLECULES, PHOTOELECTRON-SPECTRA, X-ray absorption spectra, X-ray emission spectra},
	isbn = {0020-7608},
	url = {<Go to ISI>://000255603100007},
	author = {Chong, D. P. and Segala, M. and Takahata, Y. and Baerends, E. J.}
}
@article {1361,
	title = {Density functional theory calculation of electron spectra of formaldehyde},
	journal = {Chemical Physics Letters},
	volume = {418},
	number = {1-3},
	year = {2006},
	note = {ISI Document Delivery No.: 005UMTimes Cited: 12Cited Reference Count: 30},
	month = {Jan},
	pages = {286-291},
	type = {Article},
	abstract = {Both ionization and excitation spectra for outer valence-shell electrons and inner-shell electrons of formaldehyde are calculated with density functional methods. In addition, both resonant and non-resonant X-ray emission spectra are also computed. For all of these calculations, we use four different basis sets: large and efficient sets, with and without diffuse functions. Choice of method for each type of electron spectroscopy is based on past experience. For excitation spectra, especially when the final states are Rydberg-like in nature, basis sets with diffuse functions are recommended. On the other hand, for ionization spectra and X-ray emission spectra, diffuse functions are apparently unnecessary. Available experimental data for formaldehyde enable us to judge the accuracy of the present density functional calculations. The average absolute deviation from experiment is generally about 0.3 eV or better, confirming the adequacy of our choice of method. (c) 2005 Elsevier B.V. All rights reserved.},
	keywords = {EMISSION SPECTRA, EXCITATION-ENERGIES, HYDROGEN, KRYPTON, MOLECULES, ORBITALS, photoabsorption, RAY-ABSORPTION SPECTRA, SLATER-TYPE, VERTICAL IONIZATION-POTENTIALS},
	isbn = {0009-2614},
	url = {<Go to ISI>://000234849500055},
	author = {Chong, D. P. and Takahata, Y.}
}
@article {1386,
	title = {Prediction of spectroscopic constants for diatomic molecules in the ground and excited states using time-dependent density functional theory},
	journal = {Journal of Computational Chemistry},
	volume = {27},
	number = {2},
	year = {2006},
	note = {ISI Document Delivery No.: 999IGTimes Cited: 3Cited Reference Count: 52},
	month = {Jan},
	pages = {163-173},
	type = {Article},
	abstract = {Spectroscopic constants of the ground and next seven low-lying excited states of diatomic molecules CO, N-2, P-2, and ScF were computed using the density functional theory SAOP/ATZP model, in conjunction with time-dependent density functional theory (TD-DFT) and a recently developed Slater type basis set, ATZP. Spectroscopic constants, including the equilibrium distances r(e), harmonic vibrational frequency omega(e), vibrational anharmonicity omega(e)x(e), rotational constant B-e, centrifugal distortion constant D-e, the vibration-rotation interaction constant alpha(e), and the vibrational zero-point energy E-n(0), were generated in an effort to establish a reliable database for electron spectroscopy. By comparison with experimental values and a similar model with an established larger Slater-type basis set, et-QZ3P-xD, it was found that this model provides reliably accurate results at reduced computational costs, for both the ground and excited states of the molecules. The over all errors of all eight lowest lying electronic states of the molecules under study using the effective basis set are r(e)(+/- 4\%), omega(e)(+/- 5\% mostly without exceeding +/- 20\%), omega(e)x(e)(+/- 5\% mostly without exceeding 20\%, much more accurate than a previous study on this constant of +/- 30\%), B-e(+/- 8\%), D-e(+/- 10\%), alpha(e)(+/- 10\%), and E-n(0)(+/- 10\%). The accuracy obtained using the ATZP basis set is very competitive to the larger et-QZ3P-xD basis set in particular in the ground electronic states. The overall errors in r(e), omega(e)x(e) and alpha(e) in the ground states were given by +/- 0.7, +/- 10.1, and +/- 8.4\%, respectively, using the efficient ATZP basis set, which is competitive to the errors of +/- 0.5, +/- 9.2, and +/- 9.1\%, respectively for those constants using the larger et-QZ3P-xD basis set. The latter basis set, however, needs approximately four times of the CPU time on the National Supercomputing Facilities (Australia). Due to the efficiency of the model (TD-DFT, SAOP and ATZP), it will be readily applied to study larger molecular systems. (c) 2005 Wiley Periodicals, Inc.},
	keywords = {Density Function Theroy, diatomic molecules, DIPOLE-MOMENT, ELECTRONIC-STRUCTURE, emission, EXCITATION-ENERGIES, excited, FREQUENCIES, GAUSSIAN-BASIS SETS, ground state, INDUCED POLARIZATION FUNCTIONS, ORBITALS, POTENTIALS, SPECTRA, spectroscopic constants, STATES, SURFACES},
	isbn = {0192-8651},
	url = {<Go to ISI>://000234382400005},
	author = {Falzon, C. T. and Chong, D. P. and Wang, F.}
}
@article {1050,
	title = {Functional derivative of the universal density functional in Fock space},
	journal = {Phys. Rev. A},
	volume = {70},
	number = {4},
	year = {2004},
	note = {ISI Document Delivery No.: 874AETimes Cited: 16Cited Reference Count: 117},
	month = {Oct},
	pages = {042503},
	type = {Review},
	abstract = {<p>Within the framework of zero-temperature Fock-space density-functional theory (DFT), we prove that the Gateaux functional derivative of the universal density functional, deltaF(lambda)[rho]/deltarho(r)(rho=rho0), at ground-state densities with arbitrary normalizations ((rho(0)(r))=n is an element of R+) and an electron-electron interaction strength lambda, is uniquely defined, but is discontinuous when the number of electrons n becomes an integer, thus providing a mathematically rigorous confirmation for the \&quot;derivative discontinuity\&quot; initially discovered by Perdew et al. [Phys. Rev. Lett. 49, 1691 (1982)]. However, the functional derivative of the exchange-correlation functional is continuous with respect to the number of electrons in Fock space; i.e., there is no \&quot;derivative discontinuity\&quot; for the exchange-correlation functional at an integer electron number. For a ground-state density rho(0,n)(nu,lambda)(r) of an external potential nu(r), we show that deltaF(lambda)[rho]/deltarho(r)\(nu,lambda)(rho=rho0,n)=mu(SM)(n)-nu(r), where the constant mu(SM)(n) is given by the following chain of dependences: rho(0,n)(nu,lambda)(r) bar right arrow [nu] bar right arrow E-0(nu,lambda)(n) bar right arrow mu(SM)(n) = partial derivativeE(0nu,lambda)(k)/partial derivativek\(k=n). Here [nu] is the class of the external potential nu(r) up to a real constant, and mu(SM)(n) is the chemical potential defined according to statistical mechanics. At an integer electron number N, we find that there is no freedom of adding an arbitrary constant to the value of the chemical potential mu(SM)(N), whose exact value is generally not the popular preference of the negative of Mulliken\&rsquo;s electronegativity, - 1/2 (I+A), where I and A are the first ionization potential and the first electron affinity, respectively. In addition, for any external potential converging to the same constant at infinity in all directions, we resolve that mu(SM)(N) =-I. Finally, the equality mu(DFT)=mu(SM)(n) is rigorously derived via an alternative route. where mu(DFT) is the Lagrangian multiplier used to constrain the normalization of the density in the traditional DFT approach.</p>},
	keywords = {CORRECT ASYMPTOTIC-BEHAVIOR, ELECTRONIC SYSTEMS, EXCHANGE-CORRELATION FUNCTIONALS, EXCITATION-ENERGIES, EXTENDED KOOPMANS, GROUND-STATE ENERGIES, HOMOGENEOUS FUNCTIONALS, INTERACTING, KINETIC-ENERGY, KOHN-SHAM EIGENVALUE, OCCUPATION NUMBERS, THEOREM},
	isbn = {1050-2947},
	url = {<Go to ISI>://000225322500039},
	author = {Zahariev, F. E. and Y. A. Wang*}
}
