There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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

and Fuels Changzhi Li,† Xiaochen Zhao,† Aiqin Wang,† George W. Huber,†,‡ and Tao Zhang*,† †State Key Laborotary of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China ‡Department of Chemical and Biological Engineering, University of WisconsinMadison, Madison, Wisconsin 53706, United States

Catalytic Transformation of Lignin for the Production of Chemicals and Fuels

: 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

The computer program LOBSTER (Local Orbital Basis Suite Towards Electronic-Structure Reconstruction) enables chemical-bonding analysis based on periodic plane-wave (PAW) density-functional theory (DFT) output and is applicable to a wide range of first-principles simulations in solid-state and materials chemistry. LOBSTER incorporates analytic projection routines described previously in this very journal [J. Comput. Chem. 2013, 34, 2557] and offers improved functionality. It calculates, among others, atom-projected densities of states (pDOS), projected crystal orbital Hamilton population (pCOHP) curves, and the recently introduced bond-weighted distribution function (BWDF). The software is offered free-of-charge for non-commercial research. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/jcc.24300

LOBSTER: A tool to extract chemical bonding from plane-wave based DFT

Highly efficient, NiAu-catalyzed hydrogenolysis of lignin into phenolic chemicals

The adsorption of benzene on Pt(111) was analyzed using first-principles density functional theoretical cluster and periodic slab calculations. The preferred adsorption site at low coverage is the bridge(30) site with an adsorption energy of 117 kJ/mol. At the bridge(30) site, two of the C pz orbitals are well aligned for overlap with the metal dz2 and dyz orbitals, leading to a strong C−Pt bond and a strong adsorption energy. The molecule's second important site is the hollow(0) site with an adsorption energy of 75 kJ/mol. Comparing calculated and experimental vibrational frequencies confirms the preference for the bridge site at low coverage and also indicates that adsorption at the hollow(0) site becomes preferred at higher coverage. Adsorption at the hollow(30), the bridge(0) and at the atop sites was found to be unfavorable.

Density Functional Study of Benzene Adsorption on Pt(111)

A quantum chemical investigation is presented for the determination of accurate kinetic and thermodynamic parameters for hydrocarbon radical reactions. First, standard enthalpies of formation are calculated at different levels of theory for a training set of 58 hydrocarbon molecules, ranging from C1 to C10, for which experimental data are available. It is found that the CBS-QB3 method succeeds in predicting standard enthalpies of formation with a mean absolute deviation of 2.5 kJ/mol, after a systematic correction of −1.29 kJ/mol per carbon atom and −0.28 kJ/mol per hydrogen atom. Even after a systematic correction, B3LYP density functional theory calculations are not able to reach this accuracy, with mean absolute deviations of 9.2 (B3LYP/6-31G(d)) and 12.9 kJ/mol (B3LYP/6-311G(d,p)), and with increasing deviations for larger hydrocarbons. Second, high-level transition state geometries are determined for 9 carbon-centered radical additions and 6 hydrogen additions to alkenes and alkynes and 10 hydrogen a...

Ab Initio Calculations for Hydrocarbons: Enthalpy of Formation, Transition State Geometry, and Activation Energy for Radical Reactions

Excessive CO2 emissions in the atmosphere from anthropogenic activity can be divided into point sources and diffuse sources. The capture of CO2 from flue gases of large industrial installations and its conversion into fuels and chemicals with fast catalytic processes seems technically possible. Some emerging technologies are already being demonstrated on an industrial scale. Others are still being tested on a laboratory or pilot scale. These emerging chemical technologies can be implemented in a time window ranging from 5 to 20 years. The massive amounts of energy needed for capturing processes and the conversion of CO2 should come from low-carbon energy sources, such as tidal, geothermal, and nuclear energy, but also, mainly, from the sun. Synthetic methane gas that can be formed from CO2 and hydrogen gas is an attractive renewable energy carrier with an existing distribution system. Methanol offers advantages as a liquid fuel and is also a building block for the chemical industry. CO2 emissions from diffuse sources is a difficult problem to solve, particularly for CO2 emissions from road, water, and air transport, but steady progress in the development of technology for capturing CO2 from air is being made. It is impossible to ban carbon from the entire energy supply of mankind with the current technological knowledge, but a transition to a mixed carbon-hydrogen economy can reduce net CO2 emissions and ultimately lead to a CO2 -neutral world.

/pdf/the-chemical-route-to-a-carbon-dioxide-neutral-world-3elrufskv4.pdf

The Chemical Route to a Carbon Dioxide Neutral World.

Different mechanisms have been proposed for Fischer−Tropsch synthesis, the conversion of CO and H2 to long-chain alkanes. Density functional theory calculations indicate that CO activation has a barrier of 220 kJ/mol on Co(0001), and hence the concentration of surface C or CH2 species is likely too low to explain the high chain growth probability. Hydrogenation lowers the C−O dissociation barrier to 90 kJ/mol for HCO and to 68 kJ/mol for H2CO; however, CO hydrogenation has a high energy barrier of 146 kJ/mol and is +117 kJ/mol endothermic. We propose an alternative propagation cycle starting with CO insertion into surface RCH groups. The barrier for this step is 80 kJ/mol. RCHCO is subsequently hydrogenated to RCH2CHO, which undergoes C−O dissociation with a barrier of 50 kJ/mol. The hydrogenation barriers are 120 and 48 kJ/mol along the dominant reaction path. The calculated CO turnover frequency for the proposed CO insertion mechanism is 1 to 2 orders of magnitude faster the hydrogen-assisted CO activat...

Mark Saeys

Papers

Highly efficient, NiAu-catalyzed hydrogenolysis of lignin into phenolic chemicals

Density Functional Study of Benzene Adsorption on Pt(111)

Ab Initio Calculations for Hydrocarbons: Enthalpy of Formation, Transition State Geometry, and Activation Energy for Radical Reactions

The Chemical Route to a Carbon Dioxide Neutral World.

Density Functional Theory Study of the CO Insertion Mechanism for Fischer−Tropsch Synthesis over Co Catalysts