Potential Energy Surfaces and Dynamics Calculations


Book Description

The present volume is concerned with two of the central questions of chemical dynamics. What do we know about the energies of interaction of atoms and molecules with each other and with solid surfaces? How can such interaction energies be used to understand and make quantitative predictions about dynamical processes like scattering, energy transfer, and chemical reactions? It is becoming clearly recognized that the computer is leading to rapid progress in answering these questions. The computer allows probing dynamical mechanisms in fine detail and often allows us to answer questions that cannot be addressed with current experimental techniques. As we enter the 1980's, not only are more powerful and faster computers being used, but techniques and methods have been honed to a state where exciting and reliable data are being generated on a variety of systems at an unprecedented pace. The present volume presents a collection of work that illustrates the capabilities and some of the successes of this kind of computer-assisted research. In a 1978 Chemical Society Report, Frey and Walsh pointed out that "it is extremely doubtful if a calculated energy of activation for any unimolecular decomposition can replace an experimental deter mination. " However they also recorded that they "believe[d] that some of the elaborate calculations being performed at present do suggest that we may be approaching a time when a choice between reaction mechanisms will be helped by such [computational] work.




Potential Energy Surfaces


Book Description

Shows the diversity and sophistication of present knowledge of molecular collisions and the forces that govern their outcome, examining major aspects from the point of view of the potential surface. Covers such topics as angle dependent potentials, vibranic coupling, and branching ratios in simple atomic reactions.




New Theoretical Concepts for Understanding Organic Reactions


Book Description

People who attended the NATO Advanced Study Institute (ASI) entitled NEW THEORETICAL CONCEPTS FOR UNDERSTANDING ORGANIC REAC TIONS held at Sant Feliu de Gufxols on the Costa Brava of Spain had a unique experience. They have seen the evolution of the field from qualitative arguments through the generation of Potential Energy Surfaces (PES) to the use of PES in molecular dynamics. The excellent lectures that were dedicated to the various aspects of Potential Energy Surfaces clearly revealed a colossal amount of ma terial that represents our current understanding of the overall problem. It is our hope that the present volume will recreate the excitement in the readers that we all experienced during the meeting in Spain. One can say, without too much exaggeration, that chemistry has become and exercise on potential energy surfaces (PES). Structural (position of the energy minima), spectroscopic (vicinity around the minima), and reactivity (reaction path along the surface) properties may be determined from the analysis of PES. New theoretical tools, together with recent developments in computer technology and programming, have allowed to obtain a better knowledge of these surfaces, and to extract further chemical information from them, so new horizons have been added to Theoretical Organic Chemistry.




Theoretical and Computational Models for Organic Chemistry


Book Description

The papers in this volume were presented at the NATO Advanced Study Institute held in Porto Novo, Portugal, August 26 - September 8, 1990. The Institute has been able to cover a wide spectrum of the Theoretical and Computational Models for organic molecules and organic reactions, ranging from the ab initio to the more empirical approaches, in the tradition established in the previous Institutes at S. Feliu de Guixols (Spain) and Altinoluk (Turkey). The continuity with this work was achieved by inviting half of the lecturers present in those meetings. But other important subjects were also covered at Porto Novo by new lecturers, both from universities and the industry. Molecular Mechanics, Protein Structure and Unidimensional Models were introduced by the first time. The concept of building on the expertise already acquired and available, both in terms of methods and contents, to develop in new directions, was appreciated by participants and lecturers. The Institute first considered the fundamentals of molecular orbital computations and ab initio methods and the construction of Potential Energy Surfaces. These subjects were further explored in several applications related with optimization of equilibrium geometries and transition structures. Practical examples were studied in Tutorial sessions and solved in the computational projects making use of the Gaussian 88 and Gaussian 90 programs. Empirical models can be complementary to the quantum-mechanical ones in equilibrium geometry optimizations.




Small Particles and Inorganic Clusters


Book Description

A lively demonstration of the great vitality and the multidisciplinary character of cluster research and of the usefulness of synthesizing its various aspects was given at this symposium. This volume covers all aspects of the physical and chemical properties of free and supported clusters or small particles: static, dynamical, electronic, magnetic and optical properties, adsorption and chemical phenomena. It thus gives a complete overview of the status of the field and its development.




Issues in Chemical Engineering and other Chemistry Specialties: 2011 Edition


Book Description

Issues in Chemical Engineering and other Chemistry Specialties: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Chemical Engineering and other Chemistry Specialties. The editors have built Issues in Chemical Engineering and other Chemistry Specialties: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Chemical Engineering and other Chemistry Specialties in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Chemical Engineering and other Chemistry Specialties: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.




Femtochemistry


Book Description

These two volumes on Femtochemistry present a timely contribution to a field central to the understanding of the dynamics of the chemical bond. This century has witnessed great strides in time and space resolutions, down to the atomic scale, providing chemists, biologists and physicists with unprecedented opportunities for seeing microscopic structures and dynamics. Femtochemistry is concerned with the time resolution of the most elementary motions of atoms during chemical change -- bond breaking and bond making -- on the femtosecond (10-15 second) time scale. This atomic scale of time resolution has now reached the ultimate for the chemical bond and as Lord George Porter puts it, chemists are near the end of the race against time. These two volumes cover the general concepts, techniques and applications of femtochemistry.Professor Ahmed Zewail, who has made the pioneering contributions in this field, has from over 250 publications selected the articles for this anthology. These volumes begin with a commentary and a historical chronology of the milestones. He then presents a broad perspective of the current state of knowledge in femtochemistry by researchers around the world and discusses possible new directions. In the words of a colleague, "it is a must on the reading-list for all of my students ... all readers will find this to be an informative and valuable overview."The introductory articles in Volume I provide reviews for both the non-experts as well as for experts in the field. This is followed by papers on the basic concepts. For applications, elementary reactions are studied first and then complex reactions. Volume I is complete with studies of solvation dynamics, non-reactive systems, ultrafast electron diffraction and the control of chemical reactions.Volume II continues with reaction rates, the concept of elementary intramolecular vibrational-energy redistribution (IVR) and the phenomena of rotational coherence which has become a powerful tool for the determination of molecular structure via time resolution. The second volume ends with an extensive list of references, according to topics, based on work by Professor Zewail and his group at Caltech.These collected works by Professor Zewail will certainly be indispensable to both experts and beginners in the field. The author is known for his clarity and for his creative and systematic contributions. These volumes will be of interest and should prove useful to chemists, biologists and physicists. As noted by Professor J Manz (Berlin) and Professor A W Castleman, Jr. (Penn State): femtochemistry is yielding exciting new discoveries from analysis to control of chemical reactions, with applications in many domains of chemistry and related fields, e.g., physical, organic and inorganic chemistry, surface science, molecular biology, ... etc.




Femtochemistry: Ultrafast Dynamics Of The Chemical Bond (In 2 Volumes) - Volume 1


Book Description

These two volumes on Femtochemistry present a timely contribution to a field central to the understanding of the dynamics of the chemical bond. This century has witnessed great strides in time and space resolutions, down to the atomic scale, providing chemists, biologists and physicists with unprecedented opportunities for seeing microscopic structures and dynamics. Femtochemistry is concerned with the time resolution of the most elementary motions of atoms during chemical change - bond breaking and bond making - on the femtosecond (10-15 second) time scale. This atomic scale of time resolution has now reached the ultimate for the chemical bond and as Lord George Porter puts it, chemists are near the end of the race against time. These two volumes cover the general concepts, techniques and applications of femtochemistry.Professor Ahmed Zewail, who has made the pioneering contributions in this field, has from over 250 publications selected the articles for this anthology. These volumes begin with a commentary and a historical chronology of the milestones. He then presents a broad perspective of the current state of knowledge in femtochemistry by researchers around the world and discusses possible new directions. In the words of a colleague, ';it is a must on the reading-list for all of my students ...; all readers will find this to be an informative and valuable overview.';The introductory articles in Volume I provide reviews for both the non-experts as well as for experts in the field. This is followed by papers on the basic concepts. For applications, elementary reactions are studied first and then complex reactions. Volume I is complete with studies of solvation dynamics, non-reactive systems, ultrafast electron diffraction and the control of chemical reactions.Volume II continues with reaction rates, the concept of elementary intramolecular vibrational-energy redistribution (IVR) and the phenomena of rotational coherence which has become a powerful tool for the determination of molecular structure via time resolution. The second volume ends with an extensive list of references, according to topics, based on work by Professor Zewail and his group at Caltech.These collected works by Professor Zewail will certainly be indispensable to both experts and beginners in the field. The author is known for his clarity and for his creative and systematic contributions. These volumes will be of interest and should prove useful to chemists, biologists and physicists. As noted by Professor J Manz (Berlin) and Professor A W Castleman, Jr. (Penn State): femtochemistry is yielding exciting new discoveries from analysis to control of chemical reactions, with applications in many domains of chemistry and related fields, e.g., physical, organic and inorganic chemistry, surface science, molecular biology, ...; etc.




Chemical Dynamics in Extreme Environments


Book Description

As computing power increases, a growing number of macroscopic phenomena are modeled at the molecular level. Consequently, new requirements are generated for the understanding of molecular dynamics in exotic conditions. This book illustrates the importance of detailed chemical dynamics and the role it plays in the phenomenology of a number of extreme environments. Each chapter addresses one or more extreme environments, outlines the associated chemical mechanisms of relevance, and then covers the leading edge science that elucidates the chemical coupling. The chapters exhibit a balance between theory and experiment, gas phase, solid state, and surface dynamics, and geophysical and technical environments.




The Role of Rydberg States in Spectroscopy and Photochemistry


Book Description

The aim of this volume is to offer a balanced overview of molecular Rydberg spectroscopy as it has developed over recent decades. Recent evolution has split Rydberg spectroscopy into two apparently distinct fields: the one concerns the low (n=3-5) Rydberg states, the other the very high (typically EMn/EM”150) Rydberg states. The former is aimed at spectral levels where Rydberg, valence-shell, and intermediate-type states interact, with a variety of photochemical consequences. The latter considers states extremely close to the ionization limit, from whereionization is possible with a very slight amount of additional energy. Recently developed techniques make it possible to produce ions in well-defined electronic, vibrational and rotational states, including states resulting from spin-orbit or Jahn-Teller splitting. It is then possible to study the structure and reactions of such state-selected ions as well as those of the corresponding neutral molecules. These techniques amount to badly needed high resolution photoelectron spectroscopy.