"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

Simultaneous deposition of OF2 or 18OF2 diluted in argon with a beam of Li, Na, K, or Mg atoms on a salt window at 15°K produces new infrared absorptions which are due to the appropriate metal fluorides An intense absorption at 10286 cm−1 is independent of the metal used to generate the reaction, and this feature shows the appropriate oxygen‐18 shift for assignment to the OF free radical Additional bands show a metal dependence and are attributed to weakly bonded MF···OF dimers Use of isotopic mixtures shows that bands at 7140 and 4175 cm−1 using 6Li are due to a new species containing single lithium and oxygen atoms which concentration studies suggest to be the molecule LiOF

Matrix Infrared Spectrum of OF and Detection of LiOF

The argon matrix reactions of alkali chloride salts with Cl2 have been investigated through infrared and Raman spectra. In each infrared experiment, an intense product band was observed between 327 and 375 cm−1 and assigned to the antisymmetric stretching vibration ν3 of the Cl3− anion in the ion pair M+Cl3−. Raman spectra of these reaction mixtures yielded the same ν3 bands and, in addition, new signals between 253 and 276 cm−1 which are assigned to the symmetric stretching vibration ν1 of Cl3− in the M+Cl3− species. The observation of two stretching modes in the Raman spectra indicates that the Cl3− ions are asymmetric in these ion pairs. Bromine counterparts and the mixed chlorine–bromine anions were also formed, and used to verify that the anion in the M+X3− species contains three halogen atoms, with the metal ion beside the anion in an asymmetric ’’T’’ shaped structure.

Infrared and Raman spectra of the M+Cl3− ion pairs and their chlorine–bromine counterparts isolated in argon matrices

Laser-ablated V and Ti atoms react with CO2 molecules to give primarily the insertion products, OMCO and O2M(CO)2, which have been isolated in a solid argon matrix. Photoisomerization of OMCO molecules to form the side-bonded OM−(η2-CO) isomers and photoionization to give the OMCO+ and OMOC+ cations proceed upon mercury arc photolysis. The product absorptions were identified by isotopic substitution and density functional calculations of isotopic frequencies.

Infrared Spectra and Density Functional Calculations for OMCO, OM−(η2-CO), OMCO+, and OMOC+ (M = V, Ti) in Solid Argon

Argon/benzene samples subjected to argon resonance photoionization during condensation at 21±1 K revealed a sharp new 552.5 nm product absorption, sharp C−2 bands and a broad 900 nm absorption. The 552.5 and 900 nm absorptions were destroyed and the C−2 bands decreased by mercury arc photolysis, which suggests that the 552.5 and 900 nm absorptions are due to molecular cations. The broad 900 nm absorption is in agreement with an earlier assignment to the intervalence transition in (C6H6)2+. Near agreement between the 552.5 nm absorption energy and the difference between the sharp origins for the first two benzene photoelectron bands invites consideration of the 552.5 nm absorption for C6H6+. A tentative assignment of the sharp, weak 552.5 nm band to the vibronically allowed 2E2g+e2u←2E1g transition of C6H6+ is in accord with deuterium isotopic shifts and predictions from the gas phase fluorescence spectra of fluorine substituted benzene cations. A strong 310 nm band system is attributed to the C6H7 radical...

Lester Andrews

Papers

Matrix Infrared Spectrum of OF and Detection of LiOF

Infrared and Raman spectra of the M+Cl3− ion pairs and their chlorine–bromine counterparts isolated in argon matrices

Infrared Spectra and Density Functional Calculations for OMCO, OM−(η2-CO), OMCO+, and OMOC+ (M = V, Ti) in Solid Argon

Argon matrix photolysis and photoionization studies of benzene. Absorption spectrum of benzene cation and benzene dimer cation

Fourier transform infrared matrix infrared spectra of the C2H2-HX and C2HX-HX hydrogen-bonded complex