I. Introduction: Conceptual vs Fundamental andComputational Aspects of DFT1793II. Fundamental and Computational Aspects of DFT 1795A. The Basics of DFT: The Hohenberg−KohnTheorems1795B. DFT as a Tool for Calculating Atomic andMolecular Properties: The Kohn−ShamEquations1796C. Electronic Chemical Potential andElectronegativity: Bridging Computational andConceptual DFT1797III. DFT-Based Concepts and Principles 1798A. General Scheme: Nalewajski’s ChargeSensitivity Analysis1798B. Concepts and Their Calculation 18001. Electronegativity and the ElectronicChemical Potential18002. Global Hardness and Softness 18023. The Electronic Fukui Function, LocalSoftness, and Softness Kernel18074. Local Hardness and Hardness Kernel 18135. The Molecular Shape FunctionsSimilarity 18146. The Nuclear Fukui Function and ItsDerivatives18167. Spin-Polarized Generalizations 18198. Solvent Effects 18209. Time Evolution of Reactivity Indices 1821C. Principles 18221. Sanderson’s Electronegativity EqualizationPrinciple18222. Pearson’s Hard and Soft Acids andBases Principle18253. The Maximum Hardness Principle 1829IV. Applications 1833A. Atoms and Functional Groups 1833B. Molecular Properties 18381. Dipole Moment, Hardness, Softness, andRelated Properties18382. Conformation 18403. Aromaticity 1840C. Reactivity 18421. Introduction 18422. Comparison of Intramolecular ReactivitySequences18443. Comparison of Intermolecular ReactivitySequences18494. Excited States 1857D. Clusters and Catalysis 1858V. Conclusions 1860VI. Glossary of Most Important Symbols andAcronyms1860VII. Acknowledgments 1861VIII. Note Added in Proof 1862IX. References 1865

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Conceptual density functional theory.

On-line monitoring of volatile organic compounds at pptv levels by means of proton-transfer-reaction mass spectrometry (PTR-MS) medical applications, food control and environmental research

Proton-transfer-reaction mass spectrometry (PTR-MS) allows real-time measurements of volatile organic compounds (VOCs) in air with a high sensitivity and a fast time response. The use of PTR-MS in atmospheric research has expanded rapidly in recent years, and much has been learned about the instrument response and specificity of the technique in the analysis of air from different regions of the atmosphere. This paper aims to review the progress that has been made. The theory of operation is described and allows the response of the instrument to be described for different operating conditions. More accurate determinations of the instrument response involve calibrations using standard mixtures, and some results are shown. Much has been learned about the specificity of PTR-MS from inter-comparison studies as well the coupling of PTR-MS with a gas chromatographic interface. The literature on this issue is reviewed and summarized for many VOCs of atmospheric interest. Some highlights of airborne measurements by PTR-MS are presented, including the results obtained in fresh and aged forest-fire and urban plumes. Finally, the recent work that is focused on improving the technique is discussed.

Measurements of volatile organic compounds in the earth's atmosphere using proton-transfer-reaction mass spectrometry.

Urban air pollution represents one of the greatest environmental challenges facing mankind in the 21st century. Noticeably, many developing countries, such as China and India, have experienced severe air pollution because of their fast-developing economy and urbanization. Globally, the urbanization trend is projected to continue: 70% of the world population will reside in urban centers by 2050, and there will exist 41 megacities (with more than 10 million inhabitants) by 2030. Air pollutants consist of a complex combination of gases and particulate matter (PM). In particular, fine PM (particles with the aerodynamic diameter smaller than 2.5 μm or PM_(2.5)) profoundly impacts
human health, visibility, the ecosystem, the weather, and the climate, and these PM effects are largely dependent on the aerosol properties, including the number concentration, size, and chemical composition. PM is emitted directly into the atmosphere (primary) or formed in the atmosphere through
gas-to-particle conversion (secondary) (Figure 1). Also,
primary and secondary PM undergoes chemical and physical
transformations and is subjected to transport, cloud processing, and removal from the atmosphere.

Formation of Urban Fine Particulate Matter

We present the fifth release of the UMIST Database for Astrochemistry (UDfA). The new reaction network contains 6173 gas-phase reactions, involving 467 species, 47 of which are new to this release. We have updated rate coefficients across all reaction types. We have included 1171 new anion reactions and updated and reviewed all photorates. In addition to the usual reaction network, we also now include, for download, state-specific deuterated rate coefficients, deuterium exchange reactions and a list of surface binding energies for many neutral species. Where possible, we have referenced the original source of all new and existing data. We have tested the main reaction network using a dark cloud model and a carbon-rich circumstellar envelope model. We present and briefly discuss the results of these models.

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The UMIST database for astrochemistry 2012

A recently reported calculation by chesnavich, Su and Bowers on classical trajectory study of thermal energy ion‐polar molecule capture collisions is further extended. (AIP)

Parametrization of the ion–polar molecule collision rate constant by trajectory calculations

A classical theory for the ion‐permanent dipole interaction is developed that takes into consideration the thermal rotational energy of the polar molecule. The theory is formulated in terms of an r‐dependent average orientation angle θ (r) between the dipole and the line of centers of collision. The technique allows quantitative determination of the capture cross section as a function of ion‐polar molecule relative velocity. In addition, capture limit rate constants are readily calculated both at thermal energies and as a function of relative energy. Charge transfer rate constants from various rare gas ions to difluorobenzene and dichloroethylene isomers have been measured at thermal energies using ion cyclotron resonance spectroscopy. Rate constants are considerably larger than predicted by the capture theories for both polar and nonpolar isomers indicating long range electron jump is a prevalent mechanism for charge transfer in these systems. The average‐dipole‐orientation theory developed in this pape...

Theory of ion‐polar molecule collisions. Comparison with experimental charge transfer reactions of rare gas ions to geometric isomers of difluorobenzene and dichloroethylene

Variational rate theory and trajectory methods are used to investigate the classical dynamics of capture on a noncentral long range potential. The ion–dipole surface is investigated in detail. An upper bound to the true thermal capture rate constant is derived using the variational approach. The upper bound is independent of the moment of inertia of the rotor and has only a multiplicative inverse square root dependence on the system reduced mass. For the ion–dipole surface the upper bound is in excellent agreement with trajectory calculations of the true capture rate constant and with experimental data on thermal heavy particle transfer rate constants between ions and polar neutrals. The trajectory calculations are done using an angular momentum conserved coordinate system which eliminates the need to solve two sets of Hamilton’s equations. A precise criterion for capture is derived and is used in the trajectory calculations. Reduced variables are introduced for the ion–dipole surface and it is shown that...

Collisions in a noncentral field: A variational and trajectory investigation of ion–dipole capture

Parameterization of the average dipole orientation theory: temperature dependence

The PES(F,Cl) analytic potential energy surface, developed previously, is used in a trajectory study of the F- + CH3Cl SN2 reaction. The trajectory SN2 rate constants, as a function of reactant relative translational energy Erel and CH3Cl temperature, are in good overall agreement with the experimental rate constants and those calculated using an ion−molecule capture/RRKM statistical model applied to PES(F,Cl). The latter agreement exists even though the reaction dynamics is decidedly nonstatistical. For high Erel the reaction is direct. At lower Erel there is evidence for formation of an ion−molecule complex; however, its lifetime is too short for complete energy randomization to occur. The velocity scattering angle is isotropic at low Erel but becomes anisotropic with forward scattering as Erel is increased. The reaction exothermicity is primarily partitioned to product vibration, in disagreement with a previous experimental study. Energy transfer from the reactants to products is very selective. Excess...

Timothy Su

Papers

Parametrization of the ion–polar molecule collision rate constant by trajectory calculations

Theory of ion‐polar molecule collisions. Comparison with experimental charge transfer reactions of rare gas ions to geometric isomers of difluorobenzene and dichloroethylene

Collisions in a noncentral field: A variational and trajectory investigation of ion–dipole capture

Parameterization of the average dipole orientation theory: temperature dependence

Trajectory studies of sn2 nucleophilic substitution. 7. f- + ch3cl fch3 +cl-