@article {2512, title = {Ab Initio Studies of Vacancy-Defected Fullerenes and Single-Walled Carbon Nanotubes}, journal = {Int. J. Quantum Chem.}, volume = {109}, number = {14}, year = {2009}, note = {ISI Document Delivery No.: 507VUTimes Cited: 1Cited Reference Count: 51Liu, Lei Vincent Tian, Wei Quan Wang, Yan Alexander6th Congress of the International-Society-for-Theoretical-Chemical-PhysicsJUL 19-24, 2008Vancouver, CANADAInt Soc Theoret Chem PhysSp. Iss. SI}, month = {Nov}, pages = {3441-3456}, type = {Proceedings Paper}, abstract = {

The structures, stabilities, and electronic properties of the single-vacancy-defected fullerenes, C-60 and C-70, and the single- and double-vacancy-defected single-walled carbon nanotubes (SWCNTs) were studied within density functional theory. The isomerization barriers for the single-vacancy-defected C,, on the triplet potential energy surface (PES) are lower than those on the singlet PES. The symmetric double-vacancy-defected (10,0) SWCNT is the most stable one among the models investigated. According to the analyses of frontier molecular orbitals (FMOs), nature bond orbitals, and local density of states, introduction of vacancy on the SWCNT decreases the band gap of semiconducting SWCNT, increases the band gap of conducting SWCNT, destructs the pi conjugation of the FMOs, and gives rise to enhanced chemical activity. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 109: 3441-3456, 2009

}, keywords = {BUCKMINSTERFULLERENE, C-60, COMPUTATIONS, CONDUCTANCE, density, EXCHANGE, FULLERENE, GENERALIZED GRADIENT APPROXIMATION, GROWTH, INHIBITION, OXIDES, single-walled carbon nanotube, vacancy defect}, isbn = {0020-7608}, url = {://000270884200026}, author = {Liu, L. V. and Tian, W. Q. and Y. A. Wang*} } @article {2677, title = {Chemistry of Single-Walled Carbon Nanotubes}, journal = {J. Comput. Theor. Nanosci.}, volume = {6}, number = {6}, year = {2009}, note = {ISI Document Delivery No.: 441BUTimes Cited: 0Cited Reference Count: 146Yeung, Charles See Tian, Wei Quart Liu, Lei Vincent Wang, Yan AlexanderSp. Iss. SI}, month = {Jun}, pages = {1213-1235}, type = {Review}, abstract = {

Single-walled carbon nanotubes (SWCNTs) have received significant attention from the scientific community over the past 15 years. Of particular interest is the potential of these macromolecules for use in molecular electronics, chemical sensory technology, nanobiology, and transition metal catalysis, For effective applications, the selective functionalization of the aforementioned all-carbon framework is necessary but has been met with considerable challenges. Herein, we review our approach to the exploration of structural and electronic properties of SWCNTs within density functional theory (DFT). Our investigations include mechanistic studies on chemical reactions of SWCNTs with defect and exploration of transition metal doped variants and their ability to adsorb small gas molecules.

}, keywords = {AB-INITIO, Defect, DOPED CARBON, ELECTRICAL-CONDUCTIVITY, ELECTROCHEMICALLY DEPOSITED FILMS, Electronic Structure, Gas Adsorption, GAUSSIAN-TYPE BASIS, GENERALIZED GRADIENT APPROXIMATION, LASER-ABLATION, MOLECULAR-ORBITAL METHODS, NANORODS, NITRIC-OXIDE, Nitrogen Monoxide, platinum, SIDEWALL FUNCTIONALIZATION, Single-Walled Carbon Nanotubes}, isbn = {1546-1955}, url = {://000265745100002}, author = {Yeung, C. S. and Tian, W. Q. and Liu, L. V. and Y. A. Wang*} } @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 = {://000266515000002}, author = {Segala, M. and Chong, D. P.} } @article {1548, title = {Density functional theory calculation of 2p core-electron binding energies of Si, P, S, Cl, and Ar in gas-phase molecules}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, volume = {151}, number = {1}, year = {2006}, note = {ISI Document Delivery No.: 017GXTimes Cited: 12Cited Reference Count: 40}, month = {Mar}, pages = {9-13}, type = {Article}, abstract = {Density functional theory (DFT) calculations have been performed on the gas-phase 2p core-electron binding energies (CEBEs) of Si and Ar in 145 cases using the following procedure: AEKS (scalar-ZORA + E-xc)/TZP//HF/6-31G(d). Delta E-KS is the difference in the total Kohn-Sham energies of the 2p-ionized cation and the neutral parent molecule calculated by DFT using different exchange-correlation functionals E-xc with triple-zeta polarized basis set, at molecular geometry optimized by HF/6-31G(d), and relativistic effects have been estimated by scalar zeroth-order regular approximation. Among the 26 functionals tested, the form of E-xc giving the best overall performance was found to be the combination of OPTX exchange and LYP correlation functionals. For that functional, the average absolute deviation (AAD) of the 145 calculated CEBEs from experiment is 0.26 cV. There are seven other exchange-correlation functionals that led to AADs of less than 0.30 eV. Some functionals give lower AADs than E-xc=OPTX-LYP for some individual elements. In the case of Si, for example, the combination of either mPW91-PBE or Becke88-Perdew86 led to an AAD of only 0.10 eV for 56 silicon-containing molecules. Another example is the case of the argon atom, for which the choice of E-xc=OPTX-Perdew86 yields a value for CEBE equal to the experimental value. (c) 2005 Elsevier B.V. All rights reserved.}, keywords = {ABSORPTION, ACCURATE, Ar(2p), ARGON, BEHAVIOR, Cl(2p), emission, ESCA, EXCHANGE-ENERGY, GENERALIZED GRADIENT APPROXIMATION, L-shell ionization, P(2p), POTENTIALS, RAY PHOTOELECTRON-SPECTROSCOPY, S(2p), Si(2p), SILICON, XPS}, isbn = {0368-2048}, url = {://000235683200003}, author = {Segala, M. and Takahata, Y. and Chong, D. P.} } @article {1602, title = {Search for suitable approximation methods for fullerene structure and relative stability studies: Case study with C50}, journal = {J. Chem. Phys.}, volume = {125}, number = {9}, year = {2006}, note = {ISI Document Delivery No.: 081XSTimes Cited: 13Cited Reference Count: 48Tian, Wei Quan Feng, Ji-Kang Wang, Yan Alexander Aoki, Yuriko}, month = {Sep}, pages = {094105}, type = {Article}, abstract = {

Local density approximation (LDA), several popular general gradient approximation (GGA), hybrid module based density functional theoretical methods: SVWN, BLYP, PBE, HCTH, B3LYP, PBE1PBE, B1LYP, and BHandHLYP, and some nonstandard hybrid methods are applied in geometry prediction for C-60 and C-70. HCTH with 3-21G basis set is found to be one of the best methods for fullerene structural prediction. In the predictions of relative stability of C-50 isomers, PM3 is an efficient method in the first step for sorting out the most stable isomers. HCTH with 3-21G predicts very good geometries for C-50, similar to the performance of B3LYP/6-31G(d). The gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital from the predictions of all the density functional theory methods has the following descending order: E-gap(half-and-half hybrid)\> E-gap(B3LYP)\> E-gap(HCTH)(GGA)\> E-gap(SVWN)(LDA). (c) 2006 American Institute of Physics.

}, keywords = {ADJUSTABLE-PARAMETERS, BUCKMINSTERFULLERENE, C-70, DENSITY-FUNCTIONAL THEORY, ELECTRON-DIFFRACTION, ENERGIES, GENERALIZED GRADIENT APPROXIMATION, MOLECULAR-STRUCTURE, PERFORMANCE, PHASE, SEMIEMPIRICAL METHODS}, isbn = {0021-9606}, url = {://000240351500008}, author = {W. Q. Tian* and J.-K. Feng and Wang, Y. A. and Aoki, Y.} } @article {825, title = {The calculation of field shift effects in the rotational spectra of heavy metal-containing diatomic molecules using density functional theory: comparison with experiment for the Tl-halides and Pb-chalcogenides}, journal = {Chemical Physics}, volume = {298}, number = {1-3}, year = {2004}, note = {ISI Document Delivery No.: 778AHTimes Cited: 11Cited Reference Count: 68}, month = {Mar}, pages = {205-212}, type = {Article}, abstract = {The electron densities at the Tl nucleus in T1X (where X = F, Cl, Br and I) and at the Pb nucleus in PbY (where Y = O, S, Se, Te) have been calculated using density functional theory. From these quantities the molecular field shift parameter, V-01(i) (i = Pb or Tl), in each diatomic molecule may be derived. The results show a good comparison with experimental data. In the course of this work various other spectroscopic constants have been calculated for these two classes of compounds and in so doing the performance of several model Hamiltonians and basis sets has been evaluated. Using the method developed here, field shift effects in a small number of other heavy metal-containing diatomic molecules have been evaluated and a tentative explanation for the trends observed is given. (C) 2003 Elsevier B.V. All rights reserved.}, keywords = {BORN-OPPENHEIMER APPROXIMATION, CORRECT ASYMPTOTIC-BEHAVIOR, CORRELATION-ENERGY, DUNHAM COEFFICIENTS, EXCHANGE-CORRELATION FUNCTIONALS, GENERALIZED GRADIENT APPROXIMATION, HYPERFINE CONSTANTS, ISOTOPE DEPENDENCE, ORDER, REGULAR APPROXIMATION, STATES}, isbn = {0301-0104}, url = {://000189216600022}, author = {Cooke, S. A. and Gerry, M. C. L. and Chong, D. P.} } @article {750, title = {DFT calculation of core-electron binding energies}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, volume = {133}, number = {1-3}, year = {2003}, note = {ISI Document Delivery No.: 754ZWTimes Cited: 40Cited Reference Count: 70}, month = {Nov}, pages = {69-76}, type = {Article}, abstract = {A total of 59 core-electron binding energies (CEBEs) were studied with the Amsterdam Density Functional Program (ADF) program and compared with the observed values. The results indicate that a polarized triple-zeta basis set of Slater-type orbitals is adequate for routine assessment of the performance of each method of computation. With such a basis set, seven density functionals were tested. In addition, the performance of 21 energy density functionals were computed from the density calculated with the statistical average of orbital potentials (SAOP). Among all the choices tested, the best density functional for core-electron binding energies of C to F turns out to be the combination of Perdew-Wang (1986) functional for exchange and the Perdew-Wang (1991) functional for correlation, confirming earlier studies based on contracted Gaussian-type orbitals. For this best functional, five Slater-type orbital basis sets were examined, ranging from polarized double-zeta quality to the largest set available in the ADF package. For the best functional with the best basis set, the average absolute deviation (AAD) of the calculated value from experiment is only 0.16 eV (C) 2003 Elsevier B.V. All rights reserved.}, keywords = {ADF, BASIS-SETS, CEBE, CHEMICAL-SHIFTS, CONJUGATED, core-electron binding energy, CORRECT ASYMPTOTIC-BEHAVIOR, DENSITY-FUNCTIONAL CALCULATION, DFF, ESCA, EXCHANGE-ENERGY, GENERALIZED GRADIENT APPROXIMATION, MOLECULAR CALCULATIONS, MOLECULES, PHOTOELECTRON-SPECTROSCOPY, X-RAY-EMISSION, XPS}, isbn = {0368-2048}, url = {://000187364200010}, author = {Takahata, Y. and Chong, D. P.} }