Download or read book Quantum Chemical Potential Energy Surfaces for Small Hydrocarbon Molecules written by Jukka-Pekka Jalkanen and published by . This book was released on 2003 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Potential Energy Surfaces and Dynamics Calculations written by Donald Truhlar and published by Springer. This book was released on 1981-08 with total page 878 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Exploration on Quantum Chemical Potential Energy Surfaces written by Koichi Ohno and published by Royal Society of Chemistry. This book was released on 2022-12-12 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written chemical formulas, such as C2H6O, can tell us the constituent atoms a molecule contains but they cannot differentiate between the possible geometrical arrangements (isomers) of these models. Yet the chemical properties of different isomers can vary hugely. Therefore, to understand the world of chemistry we need to ask what kind of isomers can be produced from a given atomic composition, how are isomers converted into each other, how do they decompose into smaller pieces, and how can they be made from smaller pieces? The answers to these questions will help us to discover new chemistry and new molecules. A potential energy surface (PES) describes a system, such as a molecule, based on geometrical parameters. The mathematical properties of the PES can be used to calculate probable isomer structures as well as how they are formed and how they might behave. Exploration on Quantum Chemical Potential Energy Surfaces focuses on the PES search based on quantum chemical calculations. It describes how to explore the chemical world on PES, discusses fundamental methods and specific techniques developed for efficient exploration on PES, and demonstrates several examples of the PES search for chemical structures and reaction routes.

Download or read book Properties of Chemically Interesting Potential Energy Surfaces written by Dietmar Heidrich and published by Springer. This book was released on 1991 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Potential energy surfaces written by and published by . This book was released on 1977 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Potential Energy Surfaces written by Alexander F. Sax and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Potential Energy Surfaces is a collection of lectures given at the 1996 Mariapfarr Workshop in Theoretical Chemistry, organized by Alexander F. Sax. The Mariapfarr Workshops' aim is to discuss in-depth topics in Theoretical Chemistry. The target group of these workshops is graduate students and postdocs.

Download or read book Quantum chemical studies of deposition and catalytic surface reactions written by Emil Kalered and published by Linköping University Electronic Press. This book was released on 2018-06-19 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum chemical calculations have been used to model chemical reactions in epitaxial growth of silicon carbide by chemical vapor deposition (CVD) processes and to study heterogeneous catalytic reactions for methanol synthesis. CVD is a common method to produce high-quality materials and e.g. thin films in the semiconductor industry, and one of the many usages of methanol is as a promising future renewable and sustainable energy carrier. To optimize the chemical processes it is essential to understand the reaction mechanisms. A comprehensive theoretical model for the process is therefore desired in order to be able to explore various variables that are difficult to investigate in situ. In this thesis reaction paths and reaction energies are computed using quantum chemical calculations. The quantum-chemical results can subsequently be used as input for thermodynamic, kinetic and computational fluid dynamics modelling in order to obtain data directly comparable with the experimental observations. For the CVD process, the effect of halogen addition to the gas mixture is studied by modelling the adsorption and diffusion of SiH2, SiCl2 and SiBr2 on the (0001?) 4H-SiC surface. SiH2 was found to bind strongest to the surface and SiBr2 binds slightly stronger than the SiCl2 molecule. The diffusion barrier is shown to be lower for SiH2 than for SiBr2 and SiCl2 which have similar barriers. SiBr2 and SiCl2 are found to have similar physisorption energies and bind stronger than the SiH2 molecule. Gibbs free-energy calculations also indicate that the SiC surface is not fully hydrogen terminated at CVD conditions since missing-neighboring pair of surface hydrogens is found to be common. Calculations for the (0001) surface show that SiCl, SiCl2, SiHCl, SiH, and SiH2 likely adsorb on a methylene site, but the processes are thermodynamically less favorable than their reverse reactions. However, the adsorbed products may be stabilized by subsequent surface reactions to form a larger structure. The formation of these larger structures is found to be fast enough to compete with the desorption processes. Also the Gibbs free energies for adsorption of Si atoms, SiX, SiX2, and SiHX where X is F or Br are presented. Adsorption of Si atoms is shown to be the most thermodynamically favorable reaction followed by SiX, SiHX, and SiX2, X being a halide. The results in this study suggest that the major Si contributors in the SiC–CVD process are Si atoms, SiX and SiH. Methanol can be synthesized from gaseous carbon dioxide and hydrogen using solid metal-metal oxide mixtures acting as heterogeneous catalysts. Since a large surface area of the catalyst enhances the speed of the heterogeneous reaction, the use of nanoparticles (NP) is expected to be advantageous due to the NPs’ large area to surface ratio. The plasma-induced creation of copper NPs is investigated. One important element during particle growth is the charging process where the variation of the work function (W) with particle size is a key quantity, and the variation becomes increasingly pronounced at smaller NP sizes. The work functions are computed for a set of NP charge numbers, sizes and shapes, using copper as a case study. A derived analytical expression for W is shown to give quite accurate estimates provided that the diameter of the NP is larger than about a nanometer and that the NP has relaxed to close to a spherical shape. For smaller sizes W deviates from the approximative expression, and also depends on the charge number. Some consequences of these results for NP charging process are outlined. Key reaction steps in the methanol synthesis reaction mechanism using a Cu/ZrO2 nanoparticle catalyst is investigated. Two different reaction paths for conversion of CO2 to CO is studied. The two paths result in the same complete reaction 2 CO2 ? 2 CO + O2 where ZrO2 (s) acts as a catalyst. The highest activation energies are significantly lower compared to that of the gas phase reaction. The presence of oxygen vacancies at the surface appear to be decisive for the catalytic process to be effective. Studies of the reaction kinetics show that when oxygen vacancies are present on the ZrO2 surface, carbon monoxide is produced within a microsecond. The IR spectra of CO2 and H2 interacting with ZrO2 and Cu under conditions that correspond to the catalyzed CH3OH production process is also studied experimentally and compared to results from the theoretical computations. Surface structures and gas-phase molecules are identified through the spectral lines by matching them to specific vibrational modes from the literature and from the new computational results. Several surface structures are verified and can be used to pin point surface structures in the reaction path. This gives important information that help decipher how the reaction mechanism of the CO2 conversion and ultimately may aid to improve the methanol synthesis process.

Download or read book Comparison of Ab Initio Quantum Chemistry with Experiment for Small Molecules written by R.J. Bartlett and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: At the American Chemical Society meeting in Philadelphia, Pennsylvania, U.S.A., a symposium was organized entitled, "Comparison of Ab Initio Quantum Chemistry with Experiment: State-of-the-Art." The intent of the symposium was to bring together forefront experimen talists, who perform the types of clean, penetrating experiments that are amenable to thorough theoretical analysis, with inventive theore ticians who have developed high accuracy ab initio methods that are capable of competing favorably with experiment, to assess the current applicability of theoretical methods in chemistry. Contributions from many of those speakers (see Appendix A) plus others selected for their expertise in the subject are contained in this volume. Such a book is especially timely, since with the recent develop ment of new, more accurate and powerful ab initio methods coupled with the exceptional progress achieved in computational equipment, ab initio quantum chemistry is now often able to offer a third voice to resolve experimental discrepancies, assist essentially in the interpre tation of experiments, and frequently, provide quantitatively accurate results for molecular properties that are not available from experiment.

Download or read book Potential Energy Hypersurfaces written by Paul G. Mezey and published by Elsevier Publishing Company. This book was released on 1987 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of the potential surface model has led naturally to a large number of studies on the subject, where the emphasis has usually been placed on lower dimensional problems, such as the reaction dynamics of diatomic to four-atom systems, or conformational problems restricted to few internal rotations. The purposes and methods of this book are, however, somewhat different from those of most studies on potential surface problems. The emphasis here is placed on those fundamental properties of potential energy hypersurfaces that are general for higher dimensions, that is, for larger molecules. The study of these properties requires some of the tools of global analysis that are not among the routine mathematical techniques of quantum chemists: topology, homotopy, and homology. This book provides the reader with an introduction to the fundamentals and to some of the more recent developments in the theory of potential energy hypersurfaces. The text is fairly self-contained. It requires no previous mathematical knowledge from the reader beyond that needed in an undergraduate quantum chemistry course.

Download or read book Nanofabrication Using Focused Ion and Electron Beams written by Ivo Utke and published by OUP USA. This book was released on 2012-05 with total page 830 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprehensively reviews the achievements and potentials of a minimally invasive, three-dimensional, and maskless surface structuring technique operating at nanometer scale by using the interaction of focused ion and electron beams (FIB/FEB) with surfaces and injected molecules.

Download or read book Introductory Organic Chemistry and Hydrocarbons written by Caio Lima Firme and published by CRC Press. This book was released on 2019-08-28 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: A novel proposal for teaching organic chemistry based on a broader and simplified use of quantum chemistry theories and notions of some statistical thermodynamic concepts aiming to enrich the learning process of the organic molecular properties and organic reactions. A detailed physical chemistry approach to teach organic chemistry for undergraduate students is the main aim of this book. A secondary objective is to familiarize undergraduate students with computational chemistry since most of illustrations of optimized geometries (plus some topological graphs) and information is from quantum chemistry outputs which will also enable students to obtain a deeper understanding of organic chemistry.

Download or read book Quantum Chemistry in the Age of Machine Learning written by Pavlo O. Dral and published by Elsevier. This book was released on 2022-09-16 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum chemistry is simulating atomistic systems according to the laws of quantum mechanics, and such simulations are essential for our understanding of the world and for technological progress. Machine learning revolutionizes quantum chemistry by increasing simulation speed and accuracy and obtaining new insights. However, for nonspecialists, learning about this vast field is a formidable challenge. Quantum Chemistry in the Age of Machine Learning covers this exciting field in detail, ranging from basic concepts to comprehensive methodological details to providing detailed codes and hands-on tutorials. Such an approach helps readers get a quick overview of existing techniques and provides an opportunity to learn the intricacies and inner workings of state-of-the-art methods. The book describes the underlying concepts of machine learning and quantum chemistry, machine learning potentials and learning of other quantum chemical properties, machine learning-improved quantum chemical methods, analysis of Big Data from simulations, and materials design with machine learning. Drawing on the expertise of a team of specialist contributors, this book serves as a valuable guide for both aspiring beginners and specialists in this exciting field. Compiles advances of machine learning in quantum chemistry across different areas into a single resource Provides insights into the underlying concepts of machine learning techniques that are relevant to quantum chemistry Describes, in detail, the current state-of-the-art machine learning-based methods in quantum chemistry

Download or read book Molecules in Superfluid Helium Nanodroplets written by Alkwin Slenczka and published by Springer Nature. This book was released on 2022-05-28 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book covers recent advances in experiments using the ultra-cold, very weakly perturbing superfluid environment provided by helium nanodroplets for high resolution spectroscopic, structural and dynamic studies of molecules and synthetic clusters. The recent infra-red, UV-Vis studies of radicals, molecules, clusters, ions and biomolecules, as well as laser dynamical and laser orientational studies, are reviewed. The Coulomb explosion studies of the uniquely quantum structures of small helium clusters, X-ray imaging of large droplets and electron diffraction of embedded molecules are also described. Particular emphasis is given to the synthesis and detection of new species by mass spectrometry and deposition electron microscopy.

Download or read book Quantum and Optical Dynamics of Matter for Nanotechnology written by Putz, Mihai V. and published by IGI Global. This book was released on 2013-10-31 with total page 527 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the emergence of nanoscience and technology in the 21st century, research has shifted its focus on the quantum and optical dynamical properties of matter such as atoms, molecules, and solids which are properly characterized in their dynamic state. Quantum and Optical Dynamics of Matter for Nanotechnology carefully addresses the general key concepts in this field and expands to more complex discussions on the most recent advancements and techniques related to quantum dynamics within the confines of physical chemistry. This book is an essential reference for academics, researchers, professionals, and advanced students interested in a modern discussion of a niche area of nanotechnology.

Download or read book Non covalent Interactions in Quantum Chemistry and Physics written by Alberto Otero de la Roza and published by Elsevier. This book was released on 2017-06-15 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: Non-covalent Interactions in Quantum Chemistry and Physics: Theory and Applications provides an entry point for newcomers and a standard reference for researchers publishing in the area of non-covalent interactions. Written by the leading experts in this field, the book enables experienced researchers to keep up with the most recent developments, emerging methods, and relevant applications. The book gives a comprehensive, in-depth overview of the available quantum-chemistry methods for intermolecular interactions and details the most relevant fields of application for those techniques. Theory and applications are put side-by-side, which allows the reader to gauge the strengths and weaknesses of different computational techniques. Summarizes the state-of-the-art in the computational intermolecular interactions field in a comprehensive work Introduces students and researchers from related fields to the topic of computational non-covalent interactions, providing a single unified source of information Presents the theoretical foundations of current quantum mechanical methods alongside a collection of examples on how they can be applied to solve practical problems

Download or read book Ab Initio Molecular Dynamics Analysis Based on Reduced Dimensionality Reaction Route Map written by Takuro Tsutsumi and published by Springer Nature. This book was released on 2023-12-05 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis proposes useful tools, on-the-fly trajectory mapping method and Reaction Space Projector (ReSPer), to analyze chemical reaction mechanisms by combining the reaction route map and the ab initio molecular dynamics. The key concept for the proposed tools is the Cartesian distance between pairwise molecular structures, and a practical procedure to get the optimal distance is introduced. The on-the-fly trajectory mapping method tracks the distance function between reference structures and molecular structures along the trajectory. Although this method provides fruitful insight into dynamic reaction behaviors, the visualization of reaction routes into a low-dimensional space is still challenging because of the multi-dimensionality. ReSPer successfully constructs a low-dimensional reaction space defined by mathematically-selected principal coordinates representing mutual distance relationships in the full-dimensional space. ReSPer also enables us to project trajectories into the reaction space in the reduced dimension. In this thesis, these methods are applied to several reactions, including bifurcating and photochemical reactions, revealing dynamically-allowed reaction mechanisms. This thesis provides robust and versatile tools to elucidate dynamical reaction routes on the basis of the reduced-dimensionality reaction route map and will help control chemical reaction dynamics and select descriptors for machine learning.

Download or read book Water Worlds in the Solar System written by Antony Joseph and published by Elsevier. This book was released on 2022-11-25 with total page 846 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water Worlds in the Solar System: In Search of Habitable Environments and Life is a comprehensive reference on the formation, availability, habitability potential, and astrobiological implications of water in the Solar System. The book provides understanding of the importance of water on Earth to elucidate potential water and biosignature sources on other bodies in the Solar System. It covers processes involved in the formation of Earth and its Moon, genesis of water on those bodies, events on early Earth, and other processes that are applicable to celestial bodies in the Solar System, directly correlating data available on water on other bodies to over 15 Earth analogue sites. This book forms a comprehensive overview on water in the Solar System, from formation to biosignature and habitability considerations. It is ideal for academics, researchers and students working in the field of planetary science, extraterrestrial water research and habitability potential. Presents a comprehensive reference on water in the Solar System, developing readers’ understanding of the importance and occurrence of water on Earth and beyond, all from an oceanographer’s perspective Contrasts terrestrial analogues in relation to their roles in understanding and exploring ocean worlds and habitability Includes numerous figures, illustrations, tables and videos to help readers better understand concepts covered