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Mulliken Population Analysis (mulliken + population_analysis)
Selected AbstractsCumulative ,-, interaction triggers unusually high stabilization of linear hydrocarbons inside the single-walled carbon nanotubeINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 12 2007T. C. Dinadayalane Abstract The interactions of linear hydrocarbons C2nH4 and C2nH2 (n = 1,4) with a finite-length armchair (5,5) single-walled carbon nanotube have been investigated using HF and MP2 methods in conjunction with 6-31G(d) basis set, and molecular mechanics (MM) with MM2 force field. In all cases, the results obtained at MP2/6-31G(d) level show stabilization of these supramolecular systems, contrary to the repulsive interactions obtained with the HF method. The interaction energies computed using MM with MM2 force field are in close agreement with the results obtained using the MP2/6-31G(d) level. They increase gradually as the length of linear hydrocarbon chain increases. The present study indicates that cumulative ,-, interaction is the origin for the exceptionally high stabilization of the long nanotube-hydrocarbon complexes. Mulliken population analysis reveals a very small charge transfer between the nanotube and the guest. Essentially there is no change in HOMO-LUMO energy gap by the insertion of linear hydrocarbons. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source] Ab initio calculations and analysis of chemical bonding in SrTiO3 and SrZrO3 cubic crystalsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 10 2006R. A. Evarestov Abstract The possibility of the different first-principles methods to describe the chemical bonding in SrTiO3 and SrZrO3 cubic crystals is investigated. The local properties of the electronic structure (atomic charges, bond orders, atomic delocalization indexes, and polarization fractions) were calculated with different methods: traditional Mulliken population analysis in LCAO calculations, two projection techniques in plane-wave (PW) calculations, population analysis based on Wannier-type atomic orbitals, and chemical bonding analysis based on the localized Wannier functions for occupied (valence band) LCAO states. All the techniques considered except the traditional Mulliken analysis demonstrate that the ionicity of chemical bonding in SrZrO3 is larger than in SrTiO3, in agreement with the Zr and Ti electronegativities relation and the relative bandgaps observed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Modeling the semi-empirical electrotopological index in QSPR studies for aldehydes and ketonesJOURNAL OF CHEMOMETRICS, Issue 5 2009Érica Silva Souza Abstract The semi-empirical electrotopological index, ISET, used for quantitative structure,retention relationship (QSRR) models firstly developed for alkanes and alkenes, was remodeled for organic functions such as ketones and aldehydes. The ISET values for hydrocarbons are calculated through the atomic charge values obtained from a Mulliken population analysis using the semi-empirical AM1 method and their correlation with the SETi values attributed to the different types of carbon atoms according to experimental data. For ketones and aldehydes the interactions between the molecules and the stationary phase are slowly increased relative to the hydrocarbons, due to the charge redistribution that occurs in the presence of heteroatoms. For these polar molecules the increase in the interactions was included in the calculation of the ISET values through the dipole moment of the whole molecule and also through an equivalent local dipole moment related to the net charges of the atoms of the CO and HCO functional groups. Our findings show that the best definition of an equivalent local dipole moment is clearly dependent on the specific features of the charge distribution in the polar region of the molecules (e.g. ketones and aldehydes), which allows them to be distinguished. Thus, the QSRR models for 15 aldehydes and 42 ketones obtained using the remodeled ISET were of good quality as shown by the statistical parameters. The ability of this remodeled index to include charge distribution and structural details opens a new way to study the correlations between the molecular structure and retention indices in gas chromatography. Copyright © 2009 John Wiley & Sons, Ltd. [source] Extended charge delocalization to 4-phenoxy substituent in benzhydryl solvolysis: possible contribution of non-canonical resonance structure in the cationic transition stateJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 1 2002Kwang-Ting Liu Abstract Solvolytic reactivities of 4-nitrobenzhydryl bromides (2b,5b) and chlorides (2c,5c) were studied using single- and dual-parameter Grunwald,Winstein-type correlation analyses with YBnX and YxBnX scales, respectively. Extended charge delocalization over two aryl rings at cationic transition states were found for 3 and 5, but not for 2 or 4. Calculations of the charge distributions in 3c and in the corresponding cation 3a were performed using a Hartree,Fock approximation (RHF/6-31G* basis set) and density functional models (pBP/DN** and other basis sets), respectively, on Mulliken population analysis and on electrostatic potential analysis. The possible contribution of non-canonical resonance structure is discussed. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||