"Chemists familiar with conventional quantum mechanics will applaud and benefit greatly from this particularly instructive, thorough and clearly written exposition of density functional theory: its basis, concepts, terms, implementation, and performance in diverse applications. Users of DFT for structure, energy, and molecular property computations, as well as reaction mechanism studies, are guided to the optimum choices of the most effective methods. Well done!" Paul von RaguE Schleyer "A conspicuous hole in the computational chemist's library is nicely filled by this book, which provides a wide-ranging and pragmatic view of the subject.[...It] should justifiably become the favorite text on the subject for practioneers who aim to use DFT to solve chemical problems." J. F. Stanton, J. Am. Chem. Soc. "The authors' aim is to guide the chemist through basic theoretical and related technical aspects of DFT at an easy-to-understand theoretical level. They succeed admirably." P. C. H. Mitchell, Appl. Organomet. Chem. "The authors have done an excellent service to the chemical community. [...] A Chemist's Guide to Density Functional Theory is exactly what the title suggests. It should be an invaluable source of insight and knowledge for many chemists using DFT approaches to solve chemical problems." M. Kaupp, Angew. Chem.

A Chemist's Guide to Density Functional Theory

A scheme that reduces the calculations of ground-state properties of systems of interacting particles exactly to the solution of single-particle Hartree-type equations has obvious advantages. It is not surprising, then, that the density functional formalism, which provides a way of doing this, has received much attention in the past two decades. The quality of the energy surfaces calculated using a simple local-density approximation for exchange and correlation exceeds by far the original expectations. In this work, the authors survey the formalism and some of its applications (in particular to atoms and small molecules) and discuss the reasons for the successes and failures of the local-density approximation and some of its modifications.

The density functional formalism, its applications and prospects

The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.

The Halogen Bond

The detection methods and generation mechanisms of the intrinsic reactive oxygen species (ROS), i.e., superoxide anion radical (•O2–), hydrogen peroxide (H2O2), singlet oxygen (1O2), and hydroxyl radical (•OH) in photocatalysis, were surveyed comprehensively. Consequently, the major photocatalyst used in heterogeneous photocatalytic systems was found to be TiO2. However, besides TiO2 some representative photocatalysts were also involved in the discussion. Among the various issues we focused on the detection methods and generation reactions of ROS in the aqueous suspensions of photocatalysts. On the careful account of the experimental results presented so far, we proposed the following apprehension: adsorbed •OH could be regarded as trapped holes, which are involved in a rapid adsorption–desorption equilibrium at the TiO2–solution interface. Because the equilibrium shifts to the adsorption side, trapped holes must be actually the dominant oxidation species whereas •OH in solution would exert the reactivity...

Generation and Detection of Reactive Oxygen Species in Photocatalysis

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Methane activation by laser-ablated, excited Group 11 metal atoms has been carried out, leading to generation of CH3–MH, CH3–M, and CH3–MH−, which are identified in the product infrared spectra on the basis of isotopic shifts and correlation with DFT calculated frequencies. The products reveal that C–H insertion by excited Au, Ag, and Cu readily occurs, and subsequent hydride-detachment or electron addition also follows. Each type of product has similar photochemical properties regardless of the metal. DFT computed energies reveal facile hydride dissociation and high electron affinities for the insertion complexes. The methyl metal species have the shortest C–M bonds, consistent with their highest calculated effective bond order, and the CH3–MH complexes have higher electron affinities than the metal atoms.

Infrared spectra of CH3–MH, CH3–M, and CH3–MH− prepared via methane activation by laser-ablated Au, Ag, and Cu atoms

The vibrational spectra of UBz and ThBz have been measured in solid argon. Complementary quantum chemical calculations have allowed the assignments of the vibrational spectra. According to the calculations, AcBz are stable molecules, as well as other species like BzAcBz and BzAc2Bz. Experimentally, there is no evidence for the sandwich compounds BzAcBz and BzAc2Bz due to the limitations in the reagent concentrations.

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Experimental and theoretical evidence for U(C6H6) and Th(C6H6) complexes.

Laser-ablated Pt atoms react with C2H2 upon co-condensation in excess argon and neon to form the vinylidene PtCCH2, the insertion product HPtCCH, and the strong complex or metallacyclopropene Pt−η2-(C2H2). These species are identified through 13C2H2, C2D2, and C2HD isotopic substitutions and density functional theory isotopic frequency calculations. The global energy minimum PtCCH2 is identified at 3022.4 cm-1 (C−H stretching), 1716.5 cm-1 (C−C stretching), and 707.9 cm-1 (CH2 deformation) in an argon matrix. The C−C stretching modes for Pt−η2-(C2H2) and HPtCCH are observed at 1653.7 and 2016.2 cm-1, respectively. In addition, the insertion product HPtCCH is identified by a Pt−H stretching mode at 2350.8 cm-1 and a C−C stretching mode at 2010.4 cm-1 in the neon matrix. The most stable PtCCH2 vinylidene isomer is the favored primary product. The strong complex Pd−η2-(C2H2) rearranges by 1,2 hydrogen atom migration to form the vinylidene PtCCH2 on 240−290 nm photolysis and on reaction during annealing solid...

Infrared spectra and density functional calculations for three Pt-C2H2 reaction product isomers: PtCCH2, HPtCCH, and Pt-η2-(C2H2)

Infrared detection of the PCO radical and HPCO molecule

Reactions of laser-ablated Al, Ga, In, and Tl atoms with H2O2 and with H2 + O2 mixtures diluted in argon give new absorptions in the O−H and M−O stretching and O−H bending regions, which are assigned to the metal mono-, di-, and trihydroxide molecules. Isotopic substitutions (D2O2, 18O2, 16,18O2, HD, and D2) confirm the assignments, and DFT calculations reproduce the experimental results. Infrared spectra for the Al(OH)(OD) molecule verify the calculated C2v structure. The trihydroxide molecules increase on annealing from the spontaneous reaction with a second H2O2 molecule. Aluminum atom reactions with the H2 + O2 mixtures favor the HAl(OH)2 product, suggesting that AlH3 generated by UV irradiation combines with O2 to form HAl(OH)2.

Lester Andrews

Papers

Infrared spectra of CH3–MH, CH3–M, and CH3–MH− prepared via methane activation by laser-ablated Au, Ag, and Cu atoms

Experimental and theoretical evidence for U(C6H6) and Th(C6H6) complexes.

Infrared spectra and density functional calculations for three Pt-C2H2 reaction product isomers: PtCCH2, HPtCCH, and Pt-η2-(C2H2)

Infrared detection of the PCO radical and HPCO molecule

Infrared Spectroscopic Observation of the Group 13 Metal Hydroxides, M(OH)1,2,3 (M =Al, Ga, In, and Tl) and HAl(OH)2