The calculation of accurate electron affinities (EAs) of atomic or molecular species is one of the most challenging tasks in quantum chemistry. We describe a reliable procedure for calculating the electron affinity of an atom and present results for hydrogen, boron, carbon, oxygen, and fluorine (hydrogen is included for completeness). This procedure involves the use of the recently proposed correlation‐consistent basis sets augmented with functions to describe the more diffuse character of the atomic anion coupled with a straightforward, uniform expansion of the reference space for multireference singles and doubles configuration‐interaction (MRSD‐CI) calculations. Comparison with previous results and with corresponding full CI calculations are given. The most accurate EAs obtained from the MRSD‐CI calculations are (with experimental values in parentheses) hydrogen 0.740 eV (0.754), boron 0.258 (0.277), carbon 1.245 (1.263), oxygen 1.384 (1.461), and fluorine 3.337 (3.401). The EAs obtained from the MR‐SD...

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Electron affinities of the first-row atoms revisited. Systematic basis sets and wave functions

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The hydrogen bond is the most important of all directional intermolecular interactions. It is operative in determining molecular conformation, molecular aggregation, and the function of a vast number of chemical systems ranging from inorganic to biological. Research into hydrogen bonds experienced a stagnant period in the 1980s, but re-opened around 1990, and has been in rapid development since then. In terms of modern concepts, the hydrogen bond is understood as a very broad phenomenon, and it is accepted that there are open borders to other effects. There are dozens of different types of X-H.A hydrogen bonds that occur commonly in the condensed phases, and in addition there are innumerable less common ones. Dissociation energies span more than two orders of magnitude (about 0.2-40 kcal mol(-1)). Within this range, the nature of the interaction is not constant, but its electrostatic, covalent, and dispersion contributions vary in their relative weights. The hydrogen bond has broad transition regions that merge continuously with the covalent bond, the van der Waals interaction, the ionic interaction, and also the cation-pi interaction. All hydrogen bonds can be considered as incipient proton transfer reactions, and for strong hydrogen bonds, this reaction can be in a very advanced state. In this review, a coherent survey is given on all these matters.

The hydrogen bond in the solid state.

"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

Strong Closed-Shell Interactions in Inorganic Chemistry.

Evaluation of the Density Functional Approximation on the Computation of Hydrogen Bond Interactions

The distribution of di-, tri-, and tetracoordination among the d10 ions of the group 11 metals is theoretically analyzed by means of density functional calculations on more than 150 model complexes of general formula [MXmLn](1-m) (where M = Cu, Ag, or Au; L = NH3 or PH3; X = Cl, Br, or I; m + n = 2−4). The energy of a ligand association reaction has been found to be practically determined by two contributions:  the interaction energy and the energy of deformation of the metal coordination sphere. The larger deformation energy of gold complexes compared to copper and silver ones explains the predominance of dicoordination among AuI complexes, in comparison with CuI and AgI, for which dicoordination is far less common than tri- and tetracoordination. Other experimental trends can be explained by looking at the fine details of these two energetic components.

Choice of coordination number in d10 complexes of group 11 metals.

The 2.89-A intradimer separation for cofacial [TCNE]22- (TCNE = tetracyanoethylene) dimers is twice that of conventional C−C bonds but ∼0.6 A shorter than the sum of the van der Waals radii. Experimental and computational studies best characterize the intradimer bonding as a 2-electron−4-center (2e-−4c) C−C bonding interaction (or bond). This nonconventional bonding exhibits unique spectroscopic properties (new, lower energy electronic absorption, new νCC and new and shifted νCN and δCCN vibrational absorptions, and characteristic 13C NMR chemical shifts) and is diamagnetic. [TCNE]22- is a prototype of a growing number of organic compounds that are best described by multicenter C−C bonding.

Four-center carbon-carbon bonding.

Attractive interaction with the cation overcomes the electrostatic repulsion between two tetracyanoethylene radical anions, [TCNE].- , and leads to the formation of a diamagnetic dimer [TCNE]22- , for example, in [K(glyme)]2 [TCNE]2 . The bonding is described as two-electron, four-center bonding arising from π*-π* overlap. Crystallographic as well as spectroscopic (IR and UV/Vis) features of this bonding are observed.

Juan J. Novoa

Papers

Evaluation of the Density Functional Approximation on the Computation of Hydrogen Bond Interactions

Choice of coordination number in d10 complexes of group 11 metals.

Four-center carbon-carbon bonding.

Exceptionally Long (≥2.9 Å) C−C Bonds between [TCNE]− Ions: Two‐Electron, Four‐Center π–π C−C Bonding in π‐[TCNE]22−

The C–H⋯π bonds: strength, identification, and hydrogen-bonded nature: a theoretical study

Juan J. Novoa

Papers

Evaluation of the Density Functional Approximation on the Computation of Hydrogen Bond Interactions

Choice of coordination number in d10 complexes of group 11 metals.

Four-center carbon-carbon bonding.

Exceptionally Long (≥2.9 Å) C−C Bonds between [TCNE]− Ions: Two‐Electron, Four‐Center π*–π* C−C Bonding in π‐[TCNE]22−

The C–H⋯π bonds: strength, identification, and hydrogen-bonded nature: a theoretical study

Exceptionally Long (≥2.9 Å) C−C Bonds between [TCNE]− Ions: Two‐Electron, Four‐Center π–π C−C Bonding in π‐[TCNE]22−