@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 = {://000255603100007}, author = {Chong, D. P. and Segala, M. and Takahata, Y. and Baerends, E. J.} } @article {350, title = {Interpretation of the Kohn-Sham orbital energies as approximate vertical ionization potentials}, journal = {Journal of Chemical Physics}, volume = {116}, number = {5}, year = {2002}, note = {ISI Document Delivery No.: 514CGTimes Cited: 203Cited Reference Count: 81}, month = {Feb}, pages = {1760-1772}, type = {Article}, abstract = {Theoretical analysis and results of calculations are put forward to interpret the energies -epsilon(k) of the occupied Kohn-Sham (KS) orbitals as approximate but rather accurate relaxed vertical ionization potentials (VIPs) I-k. Exact relations between epsilon(k) and I-k are established with a set of linear equations for the epsilon(k), which are expressed through I-k and the matrix elements epsilon(k)(resp) of a component of the KS exchange-correlation (xc) potential v(xc), the response potential v(resp). Although -I-k will be a leading contribution to epsilon(k), other I-jnot equalk do enter through coupling terms which are determined by the overlaps between the densities of the KS orbitals as well as by overlaps between the KS and Dyson orbital densities. The orbital energies obtained with "exact" KS potentials are compared with the experimental VIPs of the molecules N-2, CO, HF, and H2O. Very good agreement between the accurate -epsilon(k) of the outer valence KS orbitals and the corresponding VIPs is established. The average difference, approaching 0.1 eV, is about an order of magnitude smaller than for HF orbital energies. The lower valence KS levels are a few eV higher than the corresponding -I-k, and the core levels some 20 eV, in agreement with the theoretically deduced upshift of the KS levels compared to -I-k by the response potential matrix elements. Calculations of 64 molecules are performed with the approximate v(xc) obtained with the statistical averaging of (model) orbitals potentials (SAOP) and the calculated epsilon(k) are compared with 406 experimental VIPs. Reasonable agreement between the SAOP -epsilon(k) and the outer valence VIPs is found with an average deviation of about 0.4 eV. (C) 2002 American Institute of Physics.}, keywords = {ASYMPTOTIC-BEHAVIOR, DENSITY-FUNCTIONAL THEORY, DERIVATIVE DISCONTINUITIES, ELECTRON BINDING-ENERGIES, EXCHANGE-CORRELATION POTENTIALS, HE(II), LOCAL POTENTIALS, MODEL POTENTIALS, ORGANIC-MOLECULES, PHOTOELECTRON-SPECTRA, STATISTICAL AVERAGE}, isbn = {0021-9606}, url = {://000173418600003}, author = {Chong, D. P. and Gritsenko, O. V. and Baerends, E. J.} } @article {469, title = {Theoretical Auger electron and X-ray emission spectra of CO and H2O by density functional theory calculations}, journal = {Chemical Physics Letters}, volume = {352}, number = {5-6}, year = {2002}, note = {ISI Document Delivery No.: 521CHTimes Cited: 3Cited Reference Count: 33}, month = {Feb}, pages = {511-520}, type = {Article}, abstract = {We propose a new method for analysis of X-ray emission and Auger electron spectra (XES and AES) of molecules involving the valence spectra using density functional theory (DFT) calculations. To obtain the more accurate transition energies and the relative intensities, we use the total-energy difference procedure (DeltaE-KS) for all transition energies, and transform the coefficients in the LCGTO-MO scheme in the DFT to those for the linear combination of the LCGTO-AO scheme. The method is applied to the analysis of valence spectra, XES and AES for CO and H2O molecules. The simulated spectra are in a good agreement with the experimental results. (C) 20021 Published by Elsevier Science B.V.}, keywords = {ACCURATE, APPROXIMATION, BINDING-ENERGIES, MODEL, PHOTOELECTRON-SPECTRA, POLYMERS}, isbn = {0009-2614}, url = {://000173820900032}, author = {Otsuka, T. and Chong, D. P. and Maki, J. and Kawabe, H. and Endo, K.} } @article {4831, title = {Computational study of vertical ionization potentials using density functional theory and Green{\textquoteright}s function methods}, journal = {Journal of the Chinese Chemical Society}, volume = {47}, number = {1}, year = {2000}, note = {ISI Document Delivery No.: 295BRTimes Cited: 6Cited Reference Count: 44}, month = {Feb}, pages = {141-147}, type = {Article}, abstract = {Over one hundred vertical ionization potentials (VIPs) were computed using density functional theory (DFT) and Green{\textquoteright}s function (GF) based methods. The DFT approaches include the unrestricted transition state (uTS) and unrestricted diffuse ionization (uDI) approximations using the Becke88-Perdew86 exchange-correlation functional. Green{\textquoteright}s function methods include the outer-valence GF (OVGF) approach, the parametrized GF2 (pGF2), and the parametrized GF2 times screened interaction (pGW2) approximations. DFT computations of IPs using the uTS approximation was found to be nearly as accurate as those predicted using the elaborate OVGF method. The much more computationally efficient uDI approximation provides predictions of moderate accuracy and is recommended for computing IPs for larger molecules. We have observed that the average absolute deviations from a uDI calculation using poorer basis set (DZVP) and poorer geometry (AM1 optimization) is only slightly larger.}, keywords = {ALGORITHM, APPROXIMATION, density functional theory, ENERGIES, Green{\textquoteright}s function, MOLECULES, PHOTOELECTRON-SPECTRA, POTENTIALS, SPECTROSCOPY, vertical ionization}, isbn = {0009-4536}, url = {://000085946500016}, author = {Hu, C. H. and Chong, D. P.} } @article {3999, title = {The parametrized second-order Green function times screened interaction (pGW2) approximation for calculation of outer valence ionization potentials}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, volume = {85}, number = {1-2}, year = {1997}, note = {ISI Document Delivery No.: XK875Times Cited: 6Cited Reference Count: 44}, month = {Apr}, pages = {39-46}, type = {Article}, abstract = {In this paper we introduce a parameter to the second-order Green function times screened-interaction of Hedin{\textquoteright}s (GW2). The valence ionization potentials (IPs) predicted by the parametrized GW2 (pGW2) scheme compare well with experiment for a collection of 45 valence IPs for 13 small molecules. With the cc-pVTZ basis set the average absolute deviation between theoretical prediction and experiment is 0.25 eV. With the smaller cc-pVDZ basis set using the option scaling parameter (0.48) obtained from the cc-pVTZ basis set, the average absolute deviation is 0.32 eV. We have also calculated the 10 valence IPs of glycine at the geometries of its two lowest energy conformers. Our results confirm that comformer I is the global minimum, The predicted valence IPs of glycine I agree excellently with experiment (average absolute deviation 0.20 eV), and lead to are assignment of the photoelectron spectrum. (C) 1997 Elsevier Science B.V.}, keywords = {CONFIGURATION-INTERACTION, ELECTRON CORRELATION, ENERGIES, GLYCINE, Green function method, interaction, ionization potential, MOLECULES, PHOTOELECTRON-SPECTRA, QUASI-PARTICLE, QUASIPARTICLE, screened, SELF-ENERGY, SEMICONDUCTORS, SPECTROSCOPY}, isbn = {0368-2048}, url = {://A1997XK87500006}, author = {Hu, C. H. and Chong, D. P. and Casida, M. E.} } @article {2787, title = {STUDY OF TRANSITION-STATE METHODS IN THE CALCULATION OF VERTICAL IONIZATION-POTENTIALS BY LOCAL-DENSITY APPROXIMATION}, journal = {Organic Mass Spectrometry}, volume = {28}, number = {4}, year = {1993}, note = {ISI Document Delivery No.: LB163Times Cited: 37Cited Reference Count: 56}, month = {Apr}, pages = {321-326}, type = {Article}, abstract = {The vertical ionization potentials of nine small molecules were computed by the deMon density functional program and different versions of the transition-state method and the results were compared with earlier calculations and with experiment. The average absolute deviation of the 38 computed ionization potentials of the valence electrons of nine small molecules from experiment is 0.4 eV, which compares well with previous ab initio post-Hartree-Fock and semi-empirical HAM/3 calculations. The efficient methods were then used to calculate 68 ionization potentials of sixteen 22-electron molecules, with results of similar quality.}, keywords = {KOOPMANS THEOREM, MOLECULES, PERTURBATION CORRECTIONS, PHOTOELECTRON-SPECTRA, SPECTROSCOPY, X-RAY}, isbn = {0030-493X}, url = {://A1993LB16300008}, author = {Duffy, P. and Chong, D. P.} }