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 273 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 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 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing several examples, this book describes fundamental methods and techniques specific for efficient exploration on the potential energy surface by quantum chemical calculations.
Download or read book Quantum Chemical Exploration of Potential Energy Surfaces written by Christoph Herok and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Quantum Chemical Studies of Molecular Potential Energy Surfaces written by Warwick A. Shapley and published by . This book was released on 1998 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantum mechanical Study of Potential Energy Surfaces in Different Environments written by Uko Maran and published by . This book was released on 1997 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 New Horizons in Computational Chemistry Software written by Michael Filatov and published by Springer Nature. This book was released on 2022-07-30 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents the current status of software development in the field of computational and theoretical chemistry and gives an overview of the emerging trends. The challenges of maintaining the legacy codes and their adaptation to the rapidly growing hardware capabilities and the new programming environments are surveyed in a series of topical reviews written by the core developers and maintainers of the popular quantum chemistry and molecular dynamics programs. Special emphasis is given to new computational methodologies and practical aspects of their implementation and application in the computational chemistry codes. Modularity of the computational chemistry software is an emerging concept that enables to bypass the development and maintenance bottleneck of the legacy software and to customize the software using the best available computational procedures implemented in the form of self-contained modules. Perspectives on modular design of the computer programs for modeling molecular electronic structure, non-adiabatic dynamics, kinetics, as well as for data visualization are presented by the researchers actively working in the field of software development and application. This volume is of interest to quantum and computational chemists as well as experimental chemists actively using and developing computational software for their research. Chapters "MLatom 2: An Integrative Platform for Atomistic Machine Learning” and “Evolution of the Automatic Rhodopsin Modeling (ARM) Protocol" are available open access under a CC BY 4.0 License via link.springer.com.
Download or read book Development and Application of Quantum Chemical Multiconfiguration Methods Suitable for Calculating Potential Energy Surfaces of Reacting Systems written by Anders B. Heiberg and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exploring Chemical Concepts Through Theory and Computation written by Shubin Liu and published by John Wiley & Sons. This book was released on 2024-10-21 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deep, theoretical resource on the essence of chemistry, explaining the sixteen most important concepts including redox states and bond types Exploring Chemical Concepts Through Theory and Computation provides a comprehensive account of how the three widely used theoretical frameworks of valence bond theory, molecular orbital theory, and density functional theory, along with a variety of important chemical concepts, can between them describe and efficiently and reliably predict key chemical parameters and phenomena. By comparing the three main theoretical frameworks, readers will become competent in choosing the right modeling approach for their task. The authors go beyond a simple comparison of existing algorithms to show how data-driven theories can explain why chemical compounds behave the way they do, thus promoting a deeper understanding of the essence of chemistry. The text is contributed to by top theoretical and computational chemists who have turned computational chemistry into today's data-driven and application-oriented science. Exploring Chemical Concepts Through Theory and Computation discusses topics including: Orbital-based approaches, density-based approaches, chemical bonding, partial charges, atoms in molecules, oxidation states, aromaticity and antiaromaticity, and acidity and basicity Electronegativity, hardness, softness, HSAB, sigma-hole interactions, charge transport and energy transfer, and homogeneous and heterogeneous catalysis Electrophilicity, nucleophilicity, cooperativity, frustration, homochirality, and energy decomposition Chemical concepts in solids, excited states, spectroscopy and machine learning, and catalysis and machine learning, and as well as key connections between related concepts Aimed at both novice and experienced computational, theoretical, and physical chemists, Exploring Chemical Concepts Through Theory and Computation is an essential reference to gain a deeper, more advanced holistic understanding of the field of chemistry as a whole.
Download or read book Advances in Bioinformatics and Computational Biology written by João C. Setubal and published by Springer Nature. This book was released on 2020-12-19 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the Brazilian Symposium on Bioinformatics, BSB 2020, held in São Paulo, Brazil, in November 2020. Due to COVID-19 pandemic the conference was held virtually The 20 revised full papers and 5 short papers were carefully reviewed and selected from 45 submissions. The papers address a broad range of current topics in computational biology and bioinformatics.
Download or read book Chemistry at the Frontier with Physics and Computer Science written by Sergio Rampino and published by Elsevier. This book was released on 2022-05-16 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemistry at the Frontier with Physics and Computer Science: Theory and Computation shows how chemical concepts relate to their physical counterparts and can be effectively explored via computational tools. It provides a holistic overview of the intersection of these fields and offers practical examples on how to solve a chemical problem from a theoretical and computational perspective, going from theory to models, methods and implementation. Sections cover both sides of the Born-Oppenheimer approximation (nuclear dynamics and electronic structure), chemical reactions, chemical bonding, and cover theory to practice on three related physical problems (wavepacket dynamics, Hartree-Fock equations and electron-cloud redistribution). Drawing on the interdisciplinary knowledge of its expert author, this book provides a contemporary guide to theoretical and computational chemistry for all those working in chemical physics, physical chemistry and related fields. Combines a ‘big picture’ overview of chemistry as it relates to physics and computer science, including detailed guidance on tackling chemistry problems from both theoretical and computational perspectives Treats nuclear dynamics and electronic structure on the same footing in discussions of the Born-Oppenheimer approximation Includes examples of scientific programming in modern Fortran for problems related to the modeling of chemical reaction dynamics and the analysis of chemical bonding
Download or read book Properties of Chemically Interesting Potential Energy Surfaces written by Dietmar Heidrich and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contemporary chemical reaction theory is the characterization of Potential Energy Hypersurfaces (PES). The authors critically analyze chemically and mathematically suitable reaction path definitions. The book presents a simple mathematical analysis of stationary and critical points of the PES. It provides tools for studying chemical reactions by calculating reaction paths and related curves. A further aspect of the book is the dependence of PES properties on approximations used for the analysis. Recent quantum chemical calculations, particularly of single proton transfer processes, and experimental data are compared. The book addresses students and researchers in Theoretical Chemistry, Chemical Kinetics and related fields.
Download or read book Computational Approaches for Chemistry Under Extreme Conditions written by Nir Goldman and published by Springer. This book was released on 2019-02-18 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents recently developed computational approaches for the study of reactive materials under extreme physical and thermodynamic conditions. It delves into cutting edge developments in simulation methods for reactive materials, including quantum calculations spanning nanometer length scales and picosecond timescales, to reactive force fields, coarse-grained approaches, and machine learning methods spanning microns and nanoseconds and beyond. These methods are discussed in the context of a broad range of fields, including prebiotic chemistry in impacting comets, studies of planetary interiors, high pressure synthesis of new compounds, and detonations of energetic materials. The book presents a pedagogical approach for these state-of-the-art approaches, compiled into a single source for the first time. Ultimately, the volume aims to make valuable research tools accessible to experimentalists and theoreticians alike for any number of scientific efforts, spanning many different types of compounds and reactive conditions.
Download or read book Exploring the Universe From Near Space to Extra Galactic written by Banibrata Mukhopadhyay and published by Springer. This book was released on 2018-10-01 with total page 653 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Festschrift dedicated to the 60th birth anniversary of Prof. Sandip K. Chakrabarti, a well-known Indian astrophysicist, presents a collection of contributions by about fifty scientists who work on diverse topics in contemporary astrophysics and space science including new and low-cost balloon borne experiments, planetary science, astrochemistry and the origin of life, ionospheric research and earthquake predictions, relativistic astrophysics around black holes, and finally, the observational signatures and radiative properties of compact objects. All the authors are well known scholars in their respective subject and are all PhD students of Prof. Sandip K. Chakrabarti. The book demonstrates a two-dimensional evolution of research areas triggered by Sandip Chakrabarti over the past few decades. The first dimension represents the evolution and diversification of Chakrabarti’s own research in which new students were trained. A second dimension arises from the evolution of the research topics pursued by Chakrabarti’s fifty odd doctoral students, many of whom have become renowned scientists in their own right, after starting with a certain subject under Chakrabarti and then migrating to completely new subjects with dexterity. The editors have compiled and edited the articles appropriately to some extent to suit the spirit of this Festschrift on the one hand and to keep balance in diverse topics on the other. Thus this volume also provides an overview for whosoever wishes to enter the important subjects of compact objects, astrochemistry, ionospheric science or space exploration in near space. New graduates, PhD scholars, teachers and researchers will benefit from this volume. Moreover it is a record of tremendous success of a school in a range of vast topics.
Download or read book Frontiers of Chemistry written by Keith J. Laidler and published by Elsevier. This book was released on 2013-10-22 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Frontiers of Chemistry reviews the plenary and keynote lectures presented in the 28th International Union of Pure and Applied Chemistry (IUPAC) Congress. The book discusses the future development and applications of chemistry. The text is divided into two main parts, where the first part covers the plenary lectures and the second part covers the keynote lectures. Part 2 is organized into sections, according to contents, such as the role of chemistry in the solution of energy problems; the study of the environment; and the beneficiation of resources. The book will be of great interest to chemists, since it tackles topics that are significant in the advancement of the field of chemistry.
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 65 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.
