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Books > Science & Mathematics > Chemistry > Physical chemistry > Quantum & theoretical chemistry
In NMR, it is well-known that the chemical shift conveys structural informa tion, e. g. a carbonyl carbon will have a resonance frequency appreciably dif ferent from a methyl carbon, etc. The relation between structure and chemical shift is mostly established by empirical rules on the basis of prior experience. It is only quite recently that the advent of both comparatively cheap comput ing power and novel quantum chemistry approaches have provided feasible routes to calculate the chemical shift at the ab initio level for molecules of reasonable size. This raises the question whether application of these novel theoretical concepts offers a means of obtaining new structural information for the complex chain molecules one deals with in polymer science. Solid state 13C-NMR spectra of glassy amorphous polymers display broad, partially structured resonance regions that reflect the underlying disorder of the polymer chains. The chemical shift responds to the variation of the ge ometry of the chain, and the broad resonance regions can be explained by an inhomogeneous superposition of various chain geometries (and thus chem ical shifts). In this review, we present a novel approach to combine polymer chain statistical models, quantum chemistry and solid state NMR to pro vide quantitative information about the local chain geometry in amorphous polymers. The statistical model yields the relative occurrence of the various geometries, and quantum chemistry (together with a force field geometry op timization) establishes the link between geometry and chemical shift."
Since the inception of this volume, the world's nancial climate has radically changed. Theemphasishasshiftedfromboomingeconomiesandeconomicgrowth totherealityofrecessionanddiminishingoutlook. Witheconomicdownturncomes opportunity,inallareasofchemistryfromresearchanddevelopmentthroughto productregistrationandriskassessment,replacementsarebeingsoughtforcostly time-consumingprocesses. Leadingamongstthereplacementsaremodelswithtrue predictivecapability. Ofthesecomputationalmodelsarepreferred. This volume addresses a broad need within various areas of the "chemical industries", from pharmaceuticals and pesticides to personal products to provide computationalmethodstopredicttheeffects,activitiesandpropertiesofmolecules. Itaddressestheuseofmodelstodesignnewmoleculesandassesstheirfateand effectsbothtotheenvironmentandtohumanhealth. Thereisanemphasisrunning throughoutthisvolumetoproducerobustmodelssuitableforpurpose. Thevolume aimstoallowthereaderto nddataanddescriptorsanddevelop,discoverandutilise validmodels. Gdansk, ' Poland TomaszPuzyn Jackson,MS,USA JerzyLeszczynski Liverpool,UK MarkT. D. Cronin May2009 CONTENTS Part I Theory of QSAR 1 QuantitativeStructure-ActivityRelationships(QSARs)- ApplicationsandMethodology...3 Mark T. D. Cronin 1. 1. Introduction...3 1. 2. PurposeofQSAR...4 1. 3. ApplicationsofQSAR...4 1. 4. Methods...5 1. 5. TheCornerstonesofSuccessfulPredictiveModels ...7 1. 6. AValidated(Q)SARoraValidPrediction? ...9 1. 7. UsinginSilicoTechniques ...9 1. 8. NewAreasforinSilicoModels...11 1. 9. Conclusions...11 References ...11 2 TheUseofQuantumMechanicsDerivedDescriptorsin ComputationalToxicology...13 Steven J. Enoch 2. 1. Introduction...13 2. 2. TheSchrodingerEquation...15 2. 3. Hartree-FockTheory...17 2. 4. Semi-EmpiricalMethods:AM1andRM1...18 2. 5. ABInitio:DensityFunctionalTheory...19 2. 6. QSARforNon-ReactiveMechanismsofAcute(Aquatic) Toxicity...19 2. 7. QSARsforReactiveToxicityMechanisms...21 2. 7. 1. AquaticToxicityandSkinSensitisation...21 2. 7. 2. QSARsforMutagenicity ...24 2. 8. FutureDirectionsandOutlook...25 2. 9. Conclusions...26 References ...26 vii viii Contents 3 MolecularDescriptors...29 Viviana Consonni and Roberto Todeschini 3. 1. Introduction...29 3. 1. 1. De nitions...29 3. 1. 2. History...31 3. 1. 3. Theoreticalvs. ExperimentalDescriptors...33 3. 2. MolecularRepresentation ...35 3. 3. TopologicalIndexes...38 3. 3. 1. MolecularGraphs...38 3. 3. 2. De nitionandCalculationofTopologicalIndexes(TIs) 39 3. 3. 3. Graph-TheoreticalMatrixes...42 3. 3. 4. ConnectivityIndexes ...48 3. 3. 5. CharacteristicPolynomial ...50 3. 3. 6. SpectralIndexes ...53 3. 4. AutocorrelationDescriptors ...
The aim of this book is to give a simple, short, and elementary introduction to the second quantized formalism as applied to a many-electron system. It is intended for those, mainly chemists, who are familiar with traditional quantum chemistry but have not yet become acquainted with second quantization. The treatment is, in part, based on a series of seminars held by the author on the subject. It has been realized that many quantum chemists either interested in theory or in applications, being educated as chemi ts and not as physicists, have never devoted themselves to taking a course on the second quantized approach. Most available textbooks on this topic are not very easy to follow for those who are not trained in theory, or they are not detailed enough to offer a comprehensive treatment. At the same time there are several papers in quantum chemical literature which take advantage of using second quantization, and it would be worthwhile if those papers were accessible for a wider reading public. For this reason, it is intended in this survey to review the basic formalism of second quantization, and to treat some selected chapters of quantum chemistry in this language. Most derivations will be carried out in a detailed manner, so the reader need not accept gaps to understand the result.
Advances in the Theory of Atomic and Molecular Systems, is a collection of contributions presenting recent theoretical and computational developments that provide new insights into the structure, properties, and behavior of a variety of atomic and molecular systems. This volume (subtitled: Conceptual and Computational Advances in Quantum Chemistry) focuses on electronic structure theory and its foundations. This volume is an invaluable resource for faculty, graduate students, and researchers interested in theoretical and computational chemistry and physics, physical chemistry and chemical physics, molecular spectroscopy, and related areas of science and engineering.
New textbooks at all levels of chemistry appear with great regularity. Some fields like basic biochemistry, organic reaction mechanisms, and chemical thermody namics are well represented by many excellent texts, and new or revised editions are published sufficiently often to keep up with progress in research. However, some areas of chemistry, especially many of those taught at the graduate level, suffer from a real lack of up-to-date textbooks. The most serious needs occur in fields that are rapidly changing. Textbooks in these subjects usually have to be written by scientists actually involved in the research which is advancing the field. It is not often easy to persuade such individuals to set time aside to help spread the knowledge they have accumulated. Our goal, in this series, is to pinpoint areas of chemistry where recent progress has outpaced what is covered in any available textbooks, and then seek out and persuade experts in these fields to produce relatively concise but instructive introductions to their fields. These should serve the needs of one semester or one quarter graduate courses in chemistry and biochemistry. In some cases, the availability of texts in active research areas should help stimulate the creation of new courses. New York, New York CHARLES R. CANTOR Preface This book is not a traditional quantum chemistry textbook. Instead, it represents a concept that has evolved from teaching graduate courses in quantum chemistry over a number of years, and encountering students with diverse backgrounds."
This book consists of two parts, the first dealing with dissipative structures and the second with the structure and physics of chaos. The first part was written by Y. Kuramoto and the second part by H. Mori. Throughout the book, emphasis is laid on fundamental concepts and methods rather than applications, which are too numerous to be treated here. Typical physical examples, however, including nonlinear forced oscilla tors, chemical reactions with diffusion, and Benard convection in horizontal fluid layers, are discussed explicitly. Our consideration of dissipative structures is based on a phenomenolog ical reduction theory in which universal aspects of the phenomena under consideration are emphasized, while the theory of chaos is developed to treat transport phenomena, such as the mixing and diffusion of chaotic orbits, from the viewpoint of the geometrical phase space structure of chaos. The title of the original, Japanese version of the book is Sanitsu Kozo to Kaosu (Dissipative Structures and Chaos). It is part of the Iwanami Koza Gendai no Butsurigaku (Iwanami Series on Modern Physics). The first Japanese edition was published in March 1994 and the second in August 1997. We are pleased that this book has been translated into English and that it can now have an audience outside of Japan. We would like to express our gratitude to Glenn Paquette for his English translation, which has made this book more understandable than the original in many respects."
The essential introduction to the understanding of the structure of inorganic solids and materials. This revised and updated 2nd Edition looks at new developments and research results within Structural Inorganic Chemistry in a number of ways, special attention is paid to crystalline solids, elucidation and description of the spatial order of atoms within a chemical compound. Structural principles of inorganic molecules and solids are described through traditional concepts, modern bond-theoretical theories, as well as taking symmetry as a leading principle.
Brillouin-Wigner Methods for Many-Body Systems gives an introduction to many-body methods in electronic structure theory for the graduate student and post-doctoral researcher. It provides researchers in many-body physics and theoretical chemistry with an account of Brillouin-Wigner methodology as it has been developed in recent years to handle the multireference correlation problem. Moreover, the frontiers of this research field are defined. This volume is of interest to atomic and molecular physicists, physical chemists and chemical physicists, quantum chemists and condensed matter theorists, computational chemists and applied mathematicians.
In 1931 Vrey, Brickwedde, and Murphy discovered the hydrogen isotope deuterium. The isotopic enrichment was found to arise from the fact that the electrolysis oflight water is faster than of heavy water [1,2]. This success showed that although different isotopes of an element behave identically from a chemical standpoint the different isotopic masses nevertheless lead to both isotope effects on equilibrium as well as on rate constants of chemical reactions. Soon, ratios of equilibrium constants of isotopic reactions were called "equilibrium isotope effects" (EIE), ratios of isotopic rate constants "kinetic isotope effects" (KIE). Isotope effects have been found to be especially large for those elements which are directly involved in bond breaking and bond formation during the reaction studied [3]. Such effects are, therefore, referred to as "primary". Isotopic substitution in atomic sites which maintain all chemical bonds with their neighbors during the reaction of interest leads then only to smaller "secondary" isotope effects. Because of the unique mass relation between the different hydrogen isotopes hydrogen/deuterium isotope effects are particularly large and have attracted most attention. The largest contributions to these effects arise from changes in the vibrational frequencies of the reactants. The theory of equilibrium isotope effects has been founded by Vrey [4] and Bigeleisen [5,6] and has widely been accepted [3].
There have been many significant advances in time-dependent density functional theory over recent years, both in enlightening the fundamental theoretical basis of the theory, as well as in computational algorithms and applications. This book, as successor to the highly successful volume Time-Dependent Density Functional Theory (Lect. Notes Phys. 706, 2006) brings together for the first time all recent developments in a systematic and coherent way. First, a thorough pedagogical presentation of the fundamental theory is given, clarifying aspects of the original proofs and theorems, as well as presenting fresh developments that extend the theory into new realms-such as alternative proofs of the original Runge-Gross theorem, open quantum systems, and dispersion forces to name but a few. Next, all of the basic concepts are introduced sequentially and building in complexity, eventually reaching the level of open problems of interest. Contemporary applications of the theory are discussed, from real-time coupled-electron-ion dynamics, to excited-state dynamics and molecular transport. Last but not least, the authors introduce and review recent advances in computational implementation, including massively parallel architectures and graphical processing units. Special care has been taken in editing this volume as a multi-author textbook, following a coherent line of thought, and making all the relevant connections between chapters and concepts consistent throughout. As such it will prove to be the text of reference in this field, both for beginners as well as expert researchers and lecturers teaching advanced quantum mechanical methods to model complex physical systems, from molecules to nanostructures, from biocomplexes to surfaces, solids and liquids. "From the reviews of LNP 706: " "This is a well structured text, with a common set of notations and a single comprehensive and up-to-date list of references, rather than just a compilation of research articles. Because of its clear organization, the book can be used by novices (basic knowledge of ground-state DFT is assumed) and experienced users of TD-DFT, as well as developers in the field." (Anna I. Krylov, Journal of the American Chemical Society, Vol. 129 (21), 2007) "This book is a treasure of knowledge and I highly recommend it. Although it is a compilation of chapters written by many different leading researchers involved in development and application of TDDFT, the contributors have taken great care to make sure the book is pedagogically sound and the chapters complement each other ...]. It is highly accessible to any graduate student of chemistry or physics with a solid grounding in many-particle quantum mechanics, wishing to understand both the fundamental theory as well as the exponentially growing number of applications. ...] In any case, no matter what your background is, it is a must-read and an excellent reference to have on your shelf." Amazon.com, October 15, 2008, David Tempel (Cambridge, MA)"
Les hypotheses, n'en deplaise a mon contradicteur, sont l'ame des progres de la science. Louis Pasteur The concept of chirality, established 100 years ago, plays an im- portant role in almost all domains and dimensions of our recent scientific view of life. Chiral properties can be found in fundamen- tal nuclear particles, in molecules, and in the macroscopic world of living nature (plants and animals) and inanimate nature (crystals). In particular, chirality, or more precisely chiral excess, is evident in human beings. For example, the expected symmetry of the hands turns out to be functionally non-existent. Consequently chirality occurs in the technical sphere, where screws are the best-known examples, since most of them are made for right-handed people. Chirality is not confined to static objects but influences processes such as chemical reactions. The occurrence of chiral objects on different dimensional scales has been treated in the past in mutually independent frameworks. There were, however, two remarkable events from which the conclu- sion can be drawn that the appearance of chirality in various fields has a common cause. On the one hand, physicists found evidence that the well-known biomolecular homochirality can be traced back to the chirality of weak bosons. At the same time, on the other hand, the so-called thalidomide tragedy occurred when thalido- mide molecules of a certain chirality, taken by pregnant women, caused deformed children.
The quantum theory of magnetism is a well-developed part of contemporary solid-state physics. The basic concepts of this theory can be used to describe such important effects as ferromagnetic ordering oflocalized magnetic moments in crystals and ferromagnetism of metals produced by essentially delocalized electrons, as well as various types of mutual orientation of atomic magnetic moments in solids possessing different crystal lattices and compositions. In recent years, the spin-fluctuational approach has been developed, which can overcome some contradictions between "localized" and "itinerant" models in the quantum mechanics of magnetic crystals. These are only some of the principal achievements of quantum magnetic theory. Almost all of the known magnetic properties of solids can be qualitat ively explained on the basis of its concepts. Further developments should open up the possibility of reliable quantitative description of magnetic properties of solids. Unfortunately, such calculations based on model concepts appear to be very complicated and, quite often, not definite enough. The rather small number of parameters of qualitative models are usually not able to take into account the very different types of magnetic interactions that appear in crystals. Further development of magnetic theory requires quantitative information on electronic wave function in the crystal considered. This can be proved by electronic band structure and cluster calculations. In many cases the latter can be a starting point for quantitative calculations of parameters used in magnetic theory."
Mechanism of charge transport in organic solids has been an issue of intensive interests and debates for over 50 years, not only because of the applications in printing electronics, but also because of the great challenges in understanding the electronic processes in complex systems. With the fast developments of both electronic structure theory and the computational technology, the dream of predicting the charge mobility is now gradually becoming a reality. This volume describes recent progresses in Prof. Shuai's group in developing computational tools to assess the intrinsic carrier mobility for organic and carbon materials at the first-principles level. According to the electron-phonon coupling strength, the charge transport mechanism is classified into three different categories, namely, the localized hopping model, the extended band model, and the polaron model. For each of them, a corresponding theoretical approach is developed and implemented into typical examples.
Predicting molecular structure and energy and explaining the nature of bonding are central goals in quantum chemistry. With this book, the editors assert that the density functional (DF) method satisfies these goals and has come into its own as an advanced method of computational chemistry. The wealth of applications presented in the book, ranging from solid state sys tems and polymers to organic and organo-metallic molecules, metallic clus ters, and biological complexes, prove that DF is becoming a widely used computational tool in chemistry. Progress in the methodology and its imple mentation documented by the contributions in this book demonstrate that DF calculations are both accurate and efficient. In fact, the results of DF calculations may pleasantly surprise many chem ists. Even the simplest approximation of DF, the local spin density method (LSD), yields molecular structures typical of ab initio correlated methods. The next level of theory, the nonlocal spin density method, predicts the energies of molecular processes within a few kcallmol or less. Like the Hartree-Fock (HF) and configuration interaction (CI) methods, the DF method is based only on fundamental physical constants. Therefore, it does not require semiempirical parameters and can be applied to any molecular system and to metallic phases. However, DF's greatest advantage is that it can be applied to much larger systems than those approachable by tradition al ab initio methods, especially when compared with correlated ab initio methods."
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The fifth volume in this series is focused on the chemical and physical interactions between rocks undergoing metamorphism and the fluids that they generate and that pass through them. The recognition that such pro cesses can profoundly affect the course of metamorphism has resulted in a number of recent papers and we consider that it is time for a review by some of the interested parties. We hope our selection of contributors provides an adequate cross section and demonstrates some of the flavor of this rapidly developing field. A cursory examination of the volume will reveal that there are widely divergent opinions on the compositions of metamorphic fluids and on the ways in which they interact physically and chemically with the rocks through which they pass. Since our own views are extensively discussed in Chapters 4 and 8, we leave the reader to determine his own brand of the "truth. " We wish to thank D. Bird, S. Bohlen, D. Carmichael, G. Flowers, C. Foster, C. Graham, E. Perry, J. Selverstone, R. Tracy, J. Valley, and R. Wollast for their chapter reviews. Thanks are also due C. Cheverton for her editorial assistance, and the helpful staff at Springer-Verlag New York."
During the last decade there has been a renewed interest in research on supramolecular assemblies in solutions, such as micelles and microemulsions, not only because of their extensive applications in industries dealing with catalysts, detergency, biotechnology, and enhanced oil recovery, but also due to the development of new and more powerful experimental and theoretical tools for probing the microscopic behavior of these systems. Prominent among the array of the newly available experimental techniques are photon correlation spectroscopy, small-angle neutron and X-ray scattering, and neutron spin-echo and nuclear magnetic resonance spectroscopies. On the theoretical side, the traditionally emphasized thermodynamic approach to the study of the phase behavior of self-assembled systems in solutions is gradually being replaced by statistical mechanical studies of semi-micro scopic and microscopic models of the assemblies. Since the statistical mechanical approach demands as its starting point the microscopic struc tural information of the self-assembled system, the experimental determina tion of the structures of micelles and microemulsions becomes of paramount interest. In this regard the scattering techniques mentioned above have played an important role in recent years and will continue to do so in the future. In applying the scattering techniques to the supramolecular species in solution, one cannot often regard the solution to be ideal. This is because the inter-aggregate interaction is often long-ranged since it is coulombic in nature and the interparticle correlations are thus appreciable."
Our understanding of the quantitative aspects of free radical chemistry and the involvement of radicals in such areas as biology, medicine, the environment, etc., has developed spectacularly over recent years, yet the various topics are commonly discussed separately, in specific meetings and specialised publications. Free Radicals in Biology and Environment draws together two important areas of free radical chemistry, using as a bridge the fundamental physical chemistry of free radicals (spectroscopic detection of free radicals, evaluation of absolute rate constants, elucidation of mechanisms of free radical reactions and catalysis, photochemical and radiation processes, etc.). The most relevant topics covered are the EPR detection of radicals in biochemical systems and in pollutant formation and degradation, oxidation processes in biology and in the troposphere, radiation and induced damage, and atmospheric pollutants arising from incomplete combustion. Also covered are the chemistry and biochemistry of nitric oxide and peroxynitrite, the chemistry and biochemistry of DNA radicals, the role of radicals in myeloperoxidase, lignineperoxidase, radicals and cardiovascular injury, radiation and the fragmentation of cells and tissues.
Interest in the transition metal oxides with perovskite related structures goes back to the 1950s when the sodium tungsten bronzes NaxWO3 were shown to be metallic [1 ], the system Lal_xSr~MnO3 was found to contain a ferromagnetic conductive phase [2], and La0.sSr0.sCoO3 was reported to be a ferromagnetic metal, but with a peculiar magnetization of 1.5 #a/Co atom [3]. Stoichiometric oxide perovskites have the generic formula AMO3 in which the A site is at the center of a simple cubic array of M sites; the oxide ions form (180 4)) M O M bridges to give an MO3 array of corner shared MO6/2 octahedra and the larger A cations have twelvefold oxygen coordination. Mismatch between the A O and M O equilibrium bond lengths introduces internal stresses. A compressive stress on the MO3 array is accommodated by a lowering of the M O M bond angle from 180 to (180 4)); a tensile stress on the M O M bonds is accommodated by the formation of hexagonal polytypes [4].
Structure-Based Drug Design brings together scientists working on different aspects of the subject, demonstrating the necessary collaboration and interdisciplinary approach to this complex area. The focus is on X-ray crystallographic and computational approaches. The general aspects of these approaches are introduced in the first six articles. The remaining articles provide examples of the application of X-ray crystallography, molecular modelling, molecular dynamics, QSAR, database analysis, and homology modelling. The papers cover a wealth of interesting problems in the design of new and enhanced pharmaceuticals.
Providing the quantum-mechanical foundations of chemical bonding, this unique textbook emphasizes key concepts such as superposition, degeneracy of states and the role of the electron spin. An initial, concise and compact presentation of the rudiments of quantum mechanics enables readers to progress through the book with a firm grounding. Experimental examples are included to illustrate how the abstract concepts are manifest in real systems.
This monograph describes and discusses the properties of heterogeneous materials, comparing two fundamental approaches to describing and predicting materials properties. This multidisciplinary book will appeal to applied physicists, materials scientists, chemical and mechanical engineers, chemists, and applied mathematicians.
This is a self-contained advanced review offering step by step derivation of the consistent theoretical picture of hybrid modeling methods and the thorough analysis of the concepts and current practical methods of hybrid modeling based on this theory. The book presents its material in a sequential way paying attention both to the physical soundness of the approximations used and to the mathematical rigor necessary for practical developing of the robust modeling code. |
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