"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

Infrared spectra of matrix-isolated calcium-44 substituted oxides

A series of group 3 metal isocyanide complexes were prepared via the reactions of laser ablated scandium, yttrium, and lanthanum atoms with (CN)2 in an argon matrix. The product structures were identified on the basis of their characteristic infrared absorptions from isotopically labeled (CN)2 samples as well as the calculated frequencies and isotopic frequency ratios. Group 3 metal atoms reacted with (CN)2 to form M(NC)2 (M = Sc, Y, La) when the samples were subjected to λ > 220 nm irradiation. Other products such as M(NC)3 and MNC were produced together with M(NC)2 through either the reactions of M(NC)2 and (CN)2 or the loss of one CN ligand from M(NC)2. CCSD(T)//B3LYP calculations reveal that ScNC possesses a 3Δ ground state, while 1Σ+ is most stable for YNC and LaNC. All of the M(NC)2 and M(NC)3 complexes were predicted to have doublet and singlet ground states, respectively. Group 3 metal cyanides are less stable than the isocyanides by at least 4 kcal/mol at the CCSD(T) level, and their C-N stretches are much weaker than the N-C stretches of the isocyanides. No absorption can be assigned to the M(CN) x complex, which would appear between 2100 and 2250 cm-1.

Infrared Spectroscopic and Theoretical Studies of Group 3 Metal Isocyanide Molecules.

The simple methylidene and methylidyne complexes (CH2=MHX and CH[triple bond]MH2X; X = F, Cl, Br, and I) are prepared in reactions of laser-ablated Mo and W atoms with the methyl halides and investigated by matrix infrared spectroscopy and density functional theory calculations. These complex structures are photoreversible: visible irradiation converts the methylidene complex to the methylidyne complex, and UV irradiation reverses this effect via alpha-hydrogen migration. While the higher oxidation state complexes are readily formed regardless of halogen size, the Mo methylidyne complex is relatively less favored with increasing halogen size, and the W complex shows the opposite tendency. The group 6 metal methylidenes are predicted to have the most agostically distorted structures among the early transition-metal methylidenes. The computed carbon-metal bond shortens with increasing halogen size for both the methylidene and methylidyne complexes. Harmonic and anharmonic frequencies computed by DFT converge on the experimental values and thus provide support for the identification of these new Mo and W complexes.

Infrared spectra and density functional calculations of CH2 = MHX and CH[triple bond]MH2X complexes prepared in reactions of methyl halides with Mo and W atoms.

Laser-induced fluorescence studies of alkali metal atom-carbon tetrahalide matrix reaction products. Fluorescence spectra of dibromome thylene and bromochloromethylene in solid argon at 15.deg.K

Lester Andrews

Papers

Infrared spectra of matrix-isolated calcium-44 substituted oxides

Infrared Spectroscopic and Theoretical Studies of Group 3 Metal Isocyanide Molecules.

Infrared spectra and density functional calculations of CH2 = MHX and CH[triple bond]MH2X complexes prepared in reactions of methyl halides with Mo and W atoms.

Laser-induced fluorescence studies of alkali metal atom-carbon tetrahalide matrix reaction products. Fluorescence spectra of dibromome thylene and bromochloromethylene in solid argon at 15.deg.K

Infrared spectra of the intramolecular hydrogen-bonded difluorohaloform anions in solid argon