"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

Codeposition of Ar/HF and Ar/N2 samples at 10 K produced the N2‐‐H–F complex as evidenced by a very strong H–F stretching fundamental at 3881.4 cm−1 and a weak new 2332.1 cm−1 band assigned here to the N 3/4 N stretching fundamental based on 14,15N2 and 15N2 substitution. A blue DF shift to 2332. 8 cm−1 indicates a slightly stronger deuterium bond in these floppy complexes relative to the 2327.5 cm−1 Raman fundamental for N2 isolated in solid argon. Similar results were obtained for the weaker HCl and H2O complexes. Three bond stretching modes were observed for the N2‐‐H–F‐‐H–F complex.

FTIR observation of N≡N stretching fundamentals in hydrogen‐bonded complexes in solid argon

Laser-ablated U and Th atoms react with CO2 to give OUCO (1806.9, 823.2 cm-1) and OThCO (1778.4 cm-1) as major products, which are identified by isotopic substitution (13CO2, C18O2 and 12CO2 + 13CO2, C16O18O + C18O2 mixtures), doping with CCl4 as an electron trap, and comparison with frequencies from density functional calculations. The insertion reaction is spontaneous as these bands increase on annealing the neon matrix from 4 to 6 K. Further reaction of OAnCO (An = Th, U) with another CO2 molecule gives the O2An(CO)2 product, although much more so with uranium than thorium. Reaction of the metal cations with CO2 produces OUCO+ (2073.0, 881.2 cm-1) and OThCO+ (2009.9, 896.4 cm-1) with higher yield in thorium experiments. The O2An(CO)2- anions are observed for both metals again with higher yield in uranium investigations.

Reactions of Laser-Ablated U and Th with CO2: Neon Matrix Infrared Spectra and Density Functional Calculations of OUCO, OThCO, and Other Products

Uranium atoms activate methane upon ultraviolet excitation to form the methyl uranium hydride CH3-UH, which undergoes alpha-H transfer to produce uranium methylidene dihydride, CH2UH2. This rearrangement most likely occurs on an excited-quintet potential-energy surface and is followed by relaxation in the argon matrix. These simple U + CH4 reaction products are identified through isotopic substitution ((CH4)-C-13, CD4, CH2D2) and density functional theory frequency and structure calculations for the strong U-H stretching modes. Relativistic multiconfiguration (CASSCF/CASPT2) calculations substantiate the agostic distorted C-1 ground-state structure for the triplet CH2UH2 molecule. We find that uranium atoms are less reactive in methane activation than thorium atoms. Our calculations show that the CH2UH2 complex is distorted more than CH2ThH2. A favorable interaction between the low energy open-shell U(5f) sigma orbital and the agostic hydrogen contributes to the distortion in the uranium methylidene complexes. (Less)

Lester Andrews

Papers

FTIR observation of N≡N stretching fundamentals in hydrogen‐bonded complexes in solid argon

Reactions of Laser-Ablated U and Th with CO2: Neon Matrix Infrared Spectra and Density Functional Calculations of OUCO, OThCO, and Other Products

Infrared spectrum and bonding in uranium methylidene dihydride, CH2=UH2.

Infrared spectra of oxygen atom-phosphine reaction products trapped in solid argon

The Reaction of Zinc, Cadmium, and Mercury Atoms with Methane: Infrared Spectra of the Matrix-Isolated Methylmetal Hydrides