Download or read book Unified Valence Bond Theory of Electronic Structure written by N. D. Epiotis and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: The bond diagrammatic representation of molecules is the foundation of MOVB theory. To a certain extent, this kind of representation is analogous to the one on which "resonance theory" is based and this fact can be projected by a comparison of the various ways in which MOVB theory depicts a species made up of three core and two ligand MO's which define two subsystems containing a total of six electrons and the ways in which "resonance theory" (i. e. , qualitative VB theory) depicts a six-electron-six-AO species such as the pi system of CH =CH-CH=CH-CH=O. The 2 different pictorial representations are shown in Scheme 1 so that the analogies are made evident. First of all, the total MOVB diagrammatic representation of the 6/5 species is obtained by a linear combination of three complete bond diagrams, as in Al, which describe the optimal linear combination of!l! MOVB Configuration Wavefunctions (CW's). By the same token, a total VB diagrammatic representation of the 6/6 species can be obtained by writing a "dot structure", as in Bl, and taking this to mean the optimal linear combination of all VB CW's. Next, we can approxi mate the MOVB wavefunction of the 6/5 species by one complete (or detailed) bond dia gram" (A2). No simple VB representation analogy can be given in this case. Alterna tively, we can approximate the MOVB wavefunction by a linear combination of compact bond diagrams, as in A3, in the way described before.

Download or read book Unified Valence Bond Theory of Electronic Structure written by N. D. Epiotis and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Unified Valence Bond Theory of Electronic Structure Applications written by N. D. Epiotis and published by Springer. This book was released on 1983 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Unified Valence Bond Theory of Electronic Structure written by N. D. Epiotis and published by Springer. This book was released on 1982 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Unified Valence Bond Theory of Electronic Structure written by J R Larson and published by . This book was released on 1982-05-01 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Valence Bond Theory written by David Cooper and published by Elsevier. This book was released on 2002-06-05 with total page 837 pages. Available in PDF, EPUB and Kindle. Book excerpt: Valence bond (VB) theory, which builds the descriptions of molecules from those of its constituent parts, provided the first successful quantum mechanical treatments of chemical bonding. Its language and concepts permeate much of chemistry, at all levels. Various modern formulations of VB theory represent serious tools for quantum chemical studies of molecular electronic structure and reactivity. In physics, there is much VB-based work (particularly in semi-empirical form) on larger systems. Importance of TopicThe last decade has seen significant advances in methodology and a vast increase in the range of applications, with many new researchers entering the field.Why This TitleValence Bond Theory succeeds in presenting a comprehensive selection of contributions from leading valence bond (VB) theory researchers throughout the world. It focuses on the vast increase in the range of applications of methodology based on VB theory during the last decade and especially emphasizes recent advances.

Download or read book Research in Atomic Structure written by S. Fraga and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Impressive advances have been made in the study of atomic structures, at both the experimental and theoretical levels. And yet, the scarcity of information on atomic energy levels is evident At the same time there exists a need for data, because of the developments in such diverse fields as astrophysics and plasma and laser research, all of them of fundamental importance as well as practical impact. This project of research in atomic structure, consisting of three components (formulation, computer program, and numerical results), constitutes a basic and comprehensive work with a variety of uses. In its most practical application, it will yield a rather accurate prediction of the energy levels of any atomic system, of use per se or in the interpretation and confirmation of experimental results. On the other hand, it will also be of use in the comparative study of the appropriateness of the various levels of approximation and as a point of reference.

Download or read book Atoms Chemical Bonds and Bond Dissociation Energies written by Sandor Fliszar and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical bonds, their intrinsic energies in ground-state molecules and the energies required for their actual cleavage are the subject of this book. The theory, modelled after a description of valence electrons in isolated atoms, explains how intrinsic bond energies depend on the amount of electronic charge carried by the bond-forming atoms. It also explains how bond dissociation depends on these charges. While this theory vividly explains thermochemical stability, future research could benefit from a better understanding of bond dissociation: if we learn how the environment of a molecule affects its charges, we also learn how it modifies bond dissociation in that molecule. This essay is aimed at theoretical and physical-organic chemists who are looking for new perspectives to old problems.

Download or read book Overlap Determinant Method in the Theory of Pericyclic Reactions written by Robert Ponec and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: The author summarizes the development and the applications of overlap determinant method in various fields of pericyclic reactivity. The greatest advantage of this new method lies in its remarkable simplicity and flexibility owing to which it opens an interesting possibility of the systematic investigation of important mechanistic problems of pericyclic reactivity which were so far beyond the scope of other existing techniques.

Download or read book A Chemist s Guide to Valence Bond Theory written by Sason S. Shaik and published by John Wiley & Sons. This book was released on 2007-12-04 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: This reference on current VB theory and applications presents a practical system that can be applied to a variety of chemical problems in a uniform manner. After explaining basic VB theory, it discusses VB applications to bonding problems, aromaticity and antiaromaticity, the dioxygen molecule, polyradicals, excited states, organic reactions, inorganic/organometallic reactions, photochemical reactions, and catalytic reactions. With a guide for performing VB calculations, exercises and answers, and numerous solved problems, this is the premier reference for practitioners and upper-level students.

Download or read book Lecture Notes in Quantum Chemistry II written by Björn O. Roos and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first volume of Lecture Notes in Quantum Chemistry (Lecture Notes in Chemistry 58, Springer Verlag, Berlin 1992) contained a compilation of selected lectures given at the two first European Summer Schools in Quantum Chemistry (ESQC), held in southern Sweden in August 1989 and 1991, respectively. The notes were written by the teachers at the school and covered a large range of topics in ab initio quantum chemistry. After the third summer school (held in 1993) it was decided to put together a second volume with additional material. Important lecture material was excluded in the first volume and has now been added. Such added topics are: integrals and integral derivatives, SCF theory, coupled-cluster theory, relativity in quantum chemistry, and density functional theory. One chapter in the present volume contains the exercise material used at the summer school and in addition solutions to all the exercises. It is the hope of the authors that the two volumes will find good use in the scientific community as textbooks for students, who are interested in learn ing more about modern methodology in molecular quantum chemistry. The books will be used as teaching material in the European Summer Schools in Quantum Chemistry, which are presently planned. Lund in July 1994 Bjorn Roos NOTES ON HARTREE-FOCK THEORY AND RELATED TOPICS JanAlmlof Department of Chemistry University of Minnesota Minneapolis, MN 55455. USA Contents: 1 • Introduction. 2 . The Born-Oppenheimer Approximation. 3. Determinant Wavefunctions and the Pauli Principle. 4. Expectation Values With a Determinant Wavefunction.

Download or read book Perspectives in Theoretical Stereochemistry written by I. Ugi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stereochemistry is the part of chemistry that relates observable prop erties of chemical compounds to the structure of their molecules, i. e. the relative spatial arrangement of their constituent atoms. In classical stereochemistry, the spatial arrangements relevant for interpreting and predicting a given chemical property are customarily described by geometric features/ symmetries in some suitably chosen rigid model of the molecule The solution of stereochemical problems involving single molecular species is the danain of the geometry based approaches, such as the methods of classical stereochemistry, molecular mechanics and quantum chemistry. The molecules of a pure chemical compound form generally an ensemble of molecular individuals that differ in geometry and energy. Thus it is generally impossible to represent a chemical compund adequately by the geo metry of a rigid molecular model. In modern stereochemistry it is often necessary to analyze molecular relation within ensembles and families of stereoisomers and permutation isomers, including molecules whose geometric features are changing with time. Accordingly, there is definitely a need for new types of ideas, concepts, theories and techniques that are usable beyond the scope of customary methodology. This is why the present text was written.

Download or read book Computer Simulations of Protein Structures and Interactions written by Serafin Fraga and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Protein engineering endeavors to design new peptides and proteins or to change the structural and/or functional characteristics of existing ones for specific purposes, opening the way for the development of new drugs. This work develops in a comprehensive way the theoretical formulation for the methods used in computer-assisted modeling and predictions, starting from the basic concepts and proceeding to the more sophisticated methods, such as Monte Carlo and molecular dynamics. An evaluation of the approximations inherent to the simulations will allow the reader to obtain a perspective of the possible deficiencies and difficulties and approach the task with realistic expectations. Examples from the authors laboratories, as well as from the literature provide useful information.

Download or read book Chemistry Quantum Mechanics and Reductionism written by Hans Primas and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Intramolecular Diels Alder and Alder Ene Reactions written by Douglass F. Taber and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Diels-Alder reaction has long been a powerful tool in organic synthesis. In recent years, the Alder ene reaction has also achieved some prominence. From the beginning, it was apparent that the intramolecular variants of these reactions would be feasible. Many such have been reported, but the results are widely scattered in the chemical literature. This volume is an attempt to synthesize results observed to date, and to suggest directions for future development. One of the limiting factors in the application of the intramolecular Diels Alder reaction has been the development of methods for the preparation of the requisite trienes. The fIrst chapter of this volume summarizes methods for the preparation of dienes and dienophiles. Examples representative of every general approach to 1,3-dienes and to dienophilic functional group combinations have been included. There are two questions one might ask in considering the prospective cyclization of a given triene: what are the factors that govern the rate of cyclization? and, for cyclizations that lead to the creation of one or more new chiral centers, what are the factors that govern diastereoselectivity? These questions are addressed in Chapter Two. The third chapter is devoted to the all-carbon intramolecular Alder ene reaction. The tables in that chapter summarize all examples that could be found in the literature through 1981, with several additional examples from 1982. Leading references to heterocyclic ene reactions are also included in this chapter.

Download or read book GRMS or Graphical Representation of Model Spaces written by Wlodzislaw Duch and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of these notes is to give some simple tools and pictures to physicists and ' chemists working on the many-body problem. Abstract thinking and seeing have much in common - we say "I see" meaning "I understand" , for example. Most of us prefer to have a picture of an abstract object. The remarkable popularity of the Feynman diagrams, and other diagrammatic approaches to many-body problem derived thereof, may be partially due to this preference. Yet, paradoxically, the concept of a linear space, as fundamental to quantum physics as it is, has never been cast in a graphical form. We know that is a high-order contribution to a two-particle scattering process (this one invented by Cvitanovic(1984)) corresponding to a complicated matrix element. The lines in such diagrams are labeled by indices of single-particle states. When things get complicated at this level it should be good to take a global view from the perspective of the whole many-particle space. But how to visualize the space of all many-particle states ? Methods of such visualization or graphical representation of the ,spaces of interest to physicists and chemists are the main topic of this work.

Download or read book Hypervirial Theorems written by Francisco M. Fernandez and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: