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Contents for Abstracts Conference on Current Trends in Computational Chemistry 2003 11 P1 William H. Adams Intermolecular Perturbation Theory: Radii of Convergence at 19 Infinite Separation P1 Lovell Agwaramgbo, Marcus Harris, and Kimberly Bernard Experimental Analysis 20 of the Reactions of Silyl and Non-Silyl Epoxides with Basic Nucleophiles like LiAlH4 P1 R. N. Allen, Pawel Kedzierski, Andrzej Sokalski, and Jerzy Leszczynski Interactions 21 within the Active Site of Urate Oxidase P1 Valentine P. Ananikov Theoretical Study of Bicyclic Aromatic System Formation 22 from Unsaturated Linear Precursors P1 T. Aversa, C. L. Coblitz, K. A. Flanagan, M. D. Kasner, K. VanArsdale, and M. L. 23 Kasner Contributions of the Endo- and Exo- Anomeric Effect to the Conformational Energies of Substituted Cyclohexanes, 2-Oxanes, and 2-Thianes P1 Jon Baker, László Füsti-Molnar and Peter Pulay The Fourier-Transform Coulomb 26 Method P1 Anu Bamgbelu, Suely Black, and Jaroslaw J. Symczak Theoretical Study of Band 27 Gaps of Conjugated Polymer Materials with Donor-Acceptor Architectures P1 Tunna Baruah, Mark R. Pederson, Rajendra R. Zope, and Steven L. Richardson 28 Electronic Structure, Stability and Bonding of As@Ni12@As20 Cage P1 Judge Brown, Diwakar M. Pawar, and Eric A. Noe Conformational Study of 29 Cyclotridecane by Dynamic NMR Spectroscopy and Computational Methods P1 Jaroslav V. Burda, Jiří Šponer, Jana Hrabáková, Michal Zeizinger, and Jerzy 30 Leszczynski The Influence of N7 Guanine Modifications on the Strength of Watson- Crick Base Pairing and Guanine N1 Acidity: Comparison of Gas Phase and Condensed Phase Trends P1 Jaroslav Burda, Michal Zeizinger, and Jerzy Leszczynski Activation Barriers and 31 Rate Constants for Hydration of Platinum and Palladium Square Complexes: An ab Initio Study P1 Michael Cato, Jesse Edwards, Henry Joung Lee, Zhengqing You Computational 32 Studies on Novel AZT-Derivatives P1 Anthony Chuma, Dong Hee Kim, and Peter Pulay Minimizing Cost in Calculations 33 for Conformational Preferences of Small Polypeptides: Number of Residues to Consider in a Protein Model, Attenuated Basis Sets, Solvent Effects … P1 David M. Close Calculation of Hyperfine Couplings from Non-Optimized Structures 34 P1 Crystal B. Coghlan, Shelley S. Huskey, and David H. Magers Conventional Strain 37 Energy in Small Heterocycles of Carbon and Silicon P1 Lonnie D. Crosby and Henry A. Kurtz Study of Amorphous Silicon Dioxide Clusters 38 for Use in an Additive Polarizability Model P1 Jennifer L. Curry and Joseph A. Bentley The Accurate Calculation of Ro- 41 Vibrational Eigenenergies of HOD P1 Y. Daoudi, P.J. Bonifassi Correlation of Dynamic Calculations on Chiral Nonlinear 42 Optical Molecules with Measurements by Hyper-Rayleigh Scattering(HRS) and Conformational Effects 12 Conference on Current Trends in Computational Chemistry 2003 Contents for Abstracts P1 Dalephine Davis, Diwakar Pawar, and Eric A. Noe Conformational Studies of 44 Triphenylmethyl Formate and N-Triphenylmethyl Formamide P1 Yuanjian Deng and Ming-Ju Huang Capillary Electrophoretic Separation and 45 Theoretical Study of Inclusion Complexes of Sulfobutyl Ether β-Cyclodextrin with Estrogens P1 Claudia Eybl, Brian Johnson, Jesse Edwards The Correlation between Impact 47 Sensitivity and Heat of Detonation in a Unique Class of Energetic Materials P1 Peng-Dong Fan, Karol Kowalski, Maricris Lodriguito, and Piotr Piecuch New 48 Alternatives for Accurate ab Initio Calculations P1 Antonio M. Ferreira, Bob M. Moore, II, and Henry A. Kurtz Exploring the 49 Electronic Structure of Novel Cannabinoid Derivatives: New Approaches to Rational Drug Design P1 Eric W. Fisher The Distribution of Water Geometries about Polar Surface Residues 51 in Proteins, as Studied by Molecular Dynamics P1 Aviane Flood, Jacquelin McCuller, Gareth Forde, Glake Hill, and Jerzy 52 Leszczynski The Effects of Metalation on Methylated Adenine Thymine Watson- Crick Base Pair P1 Alan Ford and Peter Pulay MP2 Computational Study of van der Waals Interactions 53 Between Graphene Sheets P1 Gareth Forde, Aviane Flood, Angela Fortner, Adrian Ford, Alejandro Nazario, 54 Curinetha Hubbard, Glake Hill, Leonid Gorb, and Jerzy Leszczynski Comprehensive Study of the Effects of Methylation on Tautomeric Equilibria of Nucleic Acid Bases P1 Jason Ford-Green, Deborah Bryan, Jesse Edwards, John West, Ben M. Dunn 55 Active Site-Inhibitor Modeling Using a Customized HIV-Protease Polypeptide P1 A. D. Fortner, A. Michalkova, J. Leszczynski Theoretical Study of Adsorption of 56 Methyl-Cytosine on Dickite P1 Fillmore Freeman, Christine Fang, David Hoang, Angela C. Huang, Katie Le, 57 Thuy D. Mai, and Khue Trinhk Density Functional Theory (DFT) Study of Stannacyclohexanes and Distannacyclohexanes: Conformational Interconversions, Relative Energies, Stereoelectronic Effects, and Structures P1 Al’ona Furmanchuk, Olexandr Isayev, Leonid Gorb and Jerzy Leszczynski 60 Theoretical Investigation of 3-Methyl-Cytosine Hydration P1 Kurt R. Glaesemann and Laurence E. Fried An Improved Thermodynamic Energy 61 Estimator for Path Integral Simulations P1 Sharye Glenn, Brian Johnson, Jesse Edwards Bond Dissociation Processes in 62 Various Energetic Materials P1 Sławomir J. Grabowski, W. Andrzej Sokalski, and Jerzy Leszczynski π...H+...π 63 Hydrogen Bonds P1 Jiande Gu, Jing Wang, and Jerzy Leszczynski Hydrogen Bonding in 5-Bromouracil- 64 Adenine-5-Bromouracil-Adenine (T+AT+A) Tetrads Contents for Abstracts Conference on Current Trends in Computational Chemistry 2003 13 P1 Nasser L. Hadipour, Nasser Zamand Ab Initio Calculation of 14N NQR Parameters 65 13 1 and C, H NMR of C18H12N6 P1 Frank Hagelberg, Chuanyun Xiao, Ahmed M. El-Nahas Structures and 67 Dissociation Channels of Metal Dications Solvated by Acetonitrile Ligands P1 John A.W. Harklessa and Karl K. Irikura Multi-determinant Trial Functions in the 68 Determination of the Dissociation Energy of the Beryllium Dimer: A Quantum Monte Carlo Study P1 Robert H. Higgins Alkylation of Cytosine by cis-1-Methyl-3-hydroxyazetidinium 69 Ions: Transition States, Tautomerism, and Hydrogen Bonding P1 Glake Hill, Alex Kollias, Tomekia Simeon, Gareth Forde, William Lester, and Jerzy 70 Leszczynski Using Variational Monte Carlo for Excited States Calculations in Biological and Material Calculations P2 Patricia L. Honea, Ashley L. Ringer, and David H. Magers Conventional Strain 71 Energy in the Diazetidines and the Diphosphetanes P2 Ming-Ju Huang Theoretical Study of the Stereoisomers of Salsolinol 72 P2 Ming-Ju Huang and Manyin Yi Theoretical AM1 Studies of Inclusion Complexes of 73 Heptakis(2-o-hydroxypropyl)-β-Cyclodextrin with Alkylated Phenol P2 Danielle L. Hudson, Jeffrey A. Hinkley, Thomas C. Clancy, Melissa S. Reeves 74 Molecular Modeling of Helium Diffusion in Isomeric Polyimides P2 Shelley S. Huskey and David H. Magers Conventional Ring Strain in Unsaturated 76 Four-Membered Rings P2 Olexandr K. Isayev, Leonid Gorb, Igor Zilberberg and Jerzy Leszczynski 77 Mechanism of Nitrobenzene Reduction by Iron (II) Compounds: Density Functional Theory Study P2 Olexandr K. Isayev, Leonid Gorb, Bakhtiyor Rasulev and Jerzy Leszczynski 78 Theoretical Investigations and Structure-Toxicity Relationships of Nitroaromatic Compounds P2 Cynthia Jeffries, Glake Hill, Jerzy Leszczynski Insight into the Dispersion Energies 79 of Hydrogen and Carbon Dimer Interactions S6 Bogumil Jeziorski, Alston J. Misquitta, and Krzysztof Szalewicz Density-Functional 80 Theory Approach to van der Waals Interactions via Symmetry-Adapted Perturbation Expansion P2 Adria Johnson, Noel Matthews, and David H. Magers Computation of Conventional 81 Strain Energy in the Thiazetidines P2 Candace L. Jones, Morgan S. Ponder and Tracy P. Hamilton Computational 82 Analysis of Endo vs. Exo Retinoid Compounds P2 Dwayne C. Joseph and Bidhan C. Saha Low-Energy Single-Electron Capture in 84 5+ B and H2 Collisions P2 Isabella Karle Women in Science and Engineering. The Untapped Resource in Many 86 Countries 14 Conference on Current Trends in Computational Chemistry 2003 Contents for Abstracts P2 I.V. Kochikov, G.M. Kuramshina, D.A. Sharapov, S.A. Yagola Data Base of 87 Quantum Mechanical and Regularized Force Constants in Redundant Internal Coordinates P2 I.V. Kochikov, G.M. Kuramshina, D.A. Sharapov, S.A. Yagola Self-Consistent 91 Model for the Joint Treatment of Spectroscopic and Electron Diffraction Data S6 Walter Kohn Van der Waals Energies and Time-Dependent Density Functional 95 Theory P2 V.V. Kukueva Quantum-Chemical Research of Chemical of Elementary Radical 96 Reactions P2 H. A. Kurtz and N. P. Labello Modeling ZrxSi1-xO2: The Effects of Unique Bonding 98 Arrangements P2 Charles H. Langley and Eric A. Noe Ab Initio Studies of Performic Acid, Peracetic 101 Acid and Methyl Performate P2 Chittima Laohpongspaisan, Atchara Wijitkosoom, Surapong Pinitglang, Vudhichai 102 Parasuk, Supot Hannongbua Quantum Chemical Calculations on the Structure and Binding of Water Molecules in the HIV-1 Protease (PR) Enzyme P2 M.G. Levkovich, N.J. Abdullaev, D.N. Dalimov Modelling of Intra- and 103 Intermolecular Interactions of Glycyrrhizinic Acid P2 L. Jami Lewis and David H. Magers Binding Energies of Monovalent and Divalent 104 Cations with TNT P2 Tia Lewis, Jesse Edwards, Desiree Paramore, Henry Joung Lee, Zhengqing You 106 Solvation Studies on Novel Steroid–Nucleoside Conjugates: Alkylated Derivatives S4 Jan Linderberg The Reaction Simplex a Computational and Conceptual Tool 107 P2 M. Jeanann Lovell, G. Reid Bishop, and David H. Magers Conformational 110 Energetics of Naphthylquinolines
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  • Semiemprical Methods Chapter 5 Semiemprical Methods

    Semiemprical Methods Chapter 5 Semiemprical Methods

    Semiemprical Methods Chapter 5 Semiemprical Methods Because of the difficulties in applying ab initio methods to medium and large molecules, many semiempirical methods have been developed to treat such molecules. The earliest semiempirical methods treated only the π electrons of conjugated molecules. In the π-electron approximation, the nπ π electrons are treated separately by incorporating the effects of the σ electrons and the nuclei into some sort of effective π- electron Hamiltonian Ĥπ (recall the similar valence-electron approximation where Vi is the potential energy of the ith π electron in the field produced by the nuclei and the σ electrons. The core is everything except the π electrons. The most celebrated semiempirical π-electron theory is the Hückel molecular-orbital (HMO) method, developed in the 1930s to treat planar conjugated hydrocarbons. Here the π-electron Hamiltonian is approximated by the simpler form where Ĥeff(i) incorporates the effects of the π-electron repulsions in an average way. In fact the Hückel method does not specify any explicit form for Ĥeff(i). Since the Hückel π-electron Hamiltonian is the sum of one-electron Hamiltonians, a separation of variables is possible. We have The wave function takes no account of spin or the antisymmetry requirement. To do so, we must put each electron in a spin-orbital ui=ii. The wave function π is then written as a Slater determinant of spin-orbitals. Since Ĥeff(i) is not specified, there is no point in trying to solve above eq. directly. Instead, the variational method is used. The next assumption in the HMO method is to approximate the π MOs as LCAOs.