"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

Group 4 transition metal methylidene difluoride complexes (CH2MF2) are formed by the reaction of methylene fluoride with laser-ablated metal atoms and are isolated in an argon matrix. Isotopic substitution of the CH2F2 precursor and theoretical computations (B3LYP and CCSD) confirm product identifications and assignments. Our calculations indicate that the CH2MF2 complexes have near C2v symmetry and are considerably more stable than other possible products (CH2(μ-F)MF and CHFMHF). The primary reaction exothermicity provides more than enough energy to activate the initial bridge-bonded CH2(μ-F)MF products on the triplet potential energy surface to complete an α-F transfer to form the very stable CH2MF2 products. Analogous experiments with CHF3 produce CHFTiF2, which is not distorted at the C−H bond, whereas the heavier group 4 metals form lower-energy triplet HC÷MF3 complexes, which contain weak degenerate C(p)−M(d) π-bonding interactions. Comparisons are made with the CH2MHF methylidene species, which sho...

Group 4 Transition Metal CH2MF2, CHFMF2, and HC÷MF3 Complexes Formed by C−F Activation and α-Fluorine Transfer

Reactions of Beryllium Species with N2: Infrared Spectra and Quantum Chemical Calculations of Beryllium Dinitrogen Complexes in Solid Argon and Nitrogen

Ammonia and hydrogen iodide vapors from the thermal decomposition of NH4I were codeposited with excess neon at 5 K to form the H3N−HI complex. New 630, 1192, and 3435 cm-1 infrared absorptions are assigned to the antisymmetric N−H−I stretching, symmetric NH3 bending, and antisymmetric NH3 stretching modes of the 1:1 complex. Vibrational assignments are supported by 15NH3, ND4I, and mixed H/D isotopic substitution. Complementary experiments were done with argon, neon/argon mixtures, krypton, and nitrogen to investigate the 1:1 complex in a range of matrix environments and to compare with previous work using the reagent gases. The above modes are shifted to 592, 1259, and 3400 cm-1 in solid argon owing to an increased interaction with the more polarizable argon matrix atoms. Neon and 2% argon mixtures gave intermediate absorptions, which evolved to the pure argon values on annealing to allow diffusion. The strong nitrogen matrix infrared absorption at 1955 cm-1 shifts approximately 4 cm-1 with 15N-substitut...

Infrared Spectrum of the H3N−HI Complex in Solid Ne, Ar, Ne/Ar, Kr, and N2. Comparisons of Matrix Effects on Hydrogen-Bonded Complexes

The major HM-C≡CH and M-η(2)-C(2)H(2) products are observed in the matrix infrared spectra from reactions of laser-ablated group 3 metal atoms with acetylene, while the vinylidene product is not detected. These results reveal that coordination of group 3 metal atoms to the acetylene π-bond and H-migration from C to M readily occur during codeposition and photolysis afterward. The product absorption assigned to the La-vinylidene complex in a previous study is reassigned to one of the absorptions of La-η(2)-C(2)H(2)···C(2)H(2). Two strong Sc-H stretching absorptions are assigned to the free HSc-CCH(-) anion, in accord with a previous study, but a lower frequency counterpart is reassigned to HSc-CCH(-) coordinated to acetylene based on the increasing relative intensity of the low-frequency component at higher acetylene concentration. The group 3 metals evidently form weaker π-complexes than the group 4 metals. The addition of an electron to HM-CCH elongates the M-H and M-C bonds in the anionic species due to the lower ionic contributions to the bonding.

Lester Andrews

Papers

Group 4 Transition Metal CH2MF2, CHFMF2, and HC÷MF3 Complexes Formed by C−F Activation and α-Fluorine Transfer

Reactions of Beryllium Species with N2: Infrared Spectra and Quantum Chemical Calculations of Beryllium Dinitrogen Complexes in Solid Argon and Nitrogen

Infrared Spectrum of the H3N−HI Complex in Solid Ne, Ar, Ne/Ar, Kr, and N2. Comparisons of Matrix Effects on Hydrogen-Bonded Complexes

Infrared spectra of M-η2-C2H2, HM-C≡CH, and HM-C≡CH- prepared in reactions of laser-ablated group 3 metal atoms with acetylene.

Emission and excitation spectra of benzyl radicals in solid argon