"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

Matrix infrared spectra of Co2CO were obtained from cobalt vapors condensed with different isotopically substituted mixtures of carbon monoxide diluted in argon at 10 K. New bands at 1953.3, 488.7, 357.9, and 270.9 cm−1 are assigned to the νC–O, νM–CO, νM–C–O, and νM–M fundamentals, respectively. Computations performed using density functional theory with the generalized gradient approximation (DFT-GGA) for the exchange-correlation potential predict the lowest energy state of Co2CO to be 5A″ with the angle Co–Co–C of 116°. Our DFT-GGA vibrational frequencies of this state agree with the experimental frequencies extremely well—within 15 cm−1. Our estimate for the Co2–CO bond strength is 1.60 eV. Computed vibrational frequencies for Co2CO+ and Co2CO− are included for comparison.

Experimental and theoretical infrared spectra of Co2CO

Laser evaporation of carbon rich uranium/carbon alloy targets into condensing argon or neon matrix samples gives weak infrared absorptions that increase on annealing, which can be assigned to new uranium carbon bearing species. New bands at 827.6 cm−1 in solid argon or 871.7 cm−1 in neon become doublets with mixed carbon 12 and 13 isotopes and exhibit the 1.0381 carbon isotopic frequency ratio for the UC diatomic molecule. Another new band at 891.4 cm−1 in argon gives a three-band mixed isotopic spectrum with the 1.0366 carbon isotopic frequency ratio, which is characteristic of the anti-symmetric stretching vibration of a linear CUC molecule. No evidence was found for the lower energy cyclic U(CC) isomer. Other bands at 798.6 and 544.0 cm−1 are identified as UCH, which has a uranium-carbon triple bond similar to that in UC. Evidence is found for bicyclic U(CC)2 and tricyclic U(CC)3. This work shows that U and C atoms react spontaneously to form the uranium carbide U≡C and C≡U≡C molecules with uranium-car...

Infrared spectra and quantum chemical calculations of the uranium-carbon molecules UC, CUC, UCH, and U(CC)2.

Two interconvertible iron dioxide−dioxygen complexes were prepared and characterized by matrix isolation infrared absorption spectroscopy as well as theoretical calculations. Iron atoms react with O2 to form the inserted FeO2 molecule in solid argon only upon UV−visible light irradiation. Annealing allows the dioxygen molecules to diffuse and to react with FeO2 and form the side-on and end-on bonded dioxygen−iron dioxide complexes, (η2-O2)FeO2 and (η1-O2)FeO2. The side-on bonded structure is a peroxide complex having a singlet ground state with a nonplanar C2v symmetry. The end-on bonded isomer is characterized to be a superoxide complex with a planar 3A‘ ‘ ground state. These two isomers are photoreversible, that is, near-infrared light (λ > 850 nm) induces the conversion of the side-on bonded (η2-O2)FeO2 complex to the end-on bonded (η1-O2)FeO2 isomer and vice versa with red light irradiation (λ > 600 nm).

Formation and characterization of the photochemically interconvertible side-on and end-on bonded dioxygen-iron dioxide complexes in solid argon.

Laser-ablated Ca, Sr, and Ba atoms were co-deposited with H2 in excess argon, neon, and hydrogen to form alkaline-earth metal hydrides. The metal dihydrides (CaH2, SrH2, and BaH2) were identified i...

Metal Dihydride (MH2) and Dimer (M2H4) Structures in Solid Argon, Neon, and Hydrogen (M = Ca, Sr, and Ba): Infrared Spectra and Theoretical Calculations

Lester Andrews

Papers

Experimental and theoretical infrared spectra of Co2CO

Infrared spectra and quantum chemical calculations of the uranium-carbon molecules UC, CUC, UCH, and U(CC)2.

Formation and characterization of the photochemically interconvertible side-on and end-on bonded dioxygen-iron dioxide complexes in solid argon.

Metal Dihydride (MH2) and Dimer (M2H4) Structures in Solid Argon, Neon, and Hydrogen (M = Ca, Sr, and Ba): Infrared Spectra and Theoretical Calculations

Matrix reactions of sodium, potassium, rubidium, and cesium atoms with nitric oxide. Infrared spectra of the metal(+) nitroxide(-) species