Download or read book Chemical Theory Beyond The Born oppenheimer Paradigm Nonadiabatic Electronic And Nuclear Dynamics In Chemical Reactions written by Kazuo Takatsuka and published by World Scientific. This book was released on 2014-12-09 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique volume offers a clear perspective of the relevant methodology relating to the chemical theory of the next generation beyond the Born-Oppenheimer paradigm. It bridges the gap between cutting-edge technology of attosecond laser science and the theory of chemical reactivity. The essence of this book lies in the method of nonadiabatic electron wavepacket dynamic, which will set a new foundation for theoretical chemistry.In light of the great progress of molecular electronic structure theory (quantum chemistry), the authors show a new direction towards nonadiabatic electron dynamics, in which quantum wavepackets have been theoretically and experimentally revealed to bifurcate into pieces due to the strong kinematic interactions between electrons and nuclei.The applications range from nonadiabatic chemical reactions in photochemical dynamics to chemistry in densely quasi-degenerated electronic states that largely fluctuate through their mutual nonadiabatic couplings. The latter is termed as “chemistry without the potential energy surfaces” and thereby virtually no theoretical approach has been made yet.Restarting from such a novel foundation of theoretical chemistry, the authors cast new light even on the traditional chemical notions such as the Pauling resonance theory, proton transfer, singlet biradical reactions, and so on.
Download or read book Theoretical and Quantum Chemistry at the Dawn of the 21st Century written by Tanmoy Chakraborty and published by CRC Press. This book was released on 2018-06-19 with total page 635 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume, edited by a well-known specialist in the field of theoretical chemistry, gathers together a selection of papers on theoretical chemistry within the themes of mathematical, computational, and quantum chemistry. The authors present a rich assembly of some of the most important current research in the field of quantum chemistry in modern times. In Quantum Chemistry at the Dawn of the 21st Century, the editors aim to replicate the tradition of the fruitful Girona Workshops and Seminars, held at the University of Girona, Italy, annually for many years, which offered important scientific gatherings focusing on quantum chemistry. This volume, like the workshops, showcases a large variety of quantum chemical contributions from different points of view from some of the leading scientists in the field today. This unique volume does not pretend to provide a complete overview of quantum chemistry, but it does provide a broad set of contributions by some of the leading scientists on the field, under the expert editorship of two leaders in the field.
Download or read book Attosecond Molecular Dynamics written by Marc J J Vrakking and published by Royal Society of Chemistry. This book was released on 2018-08-31 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: Attosecond science is a new and rapidly developing research area in which molecular dynamics are studied at the timescale of a few attoseconds. Within the past decade, attosecond pump–probe spectroscopy has emerged as a powerful experimental technique that permits electron dynamics to be followed on their natural timescales. With the development of this technology, physical chemists have been able to observe and control molecular dynamics on attosecond timescales. From these observations it has been suggested that attosecond to few-femtosecond timescale charge migration may induce what has been called “post-Born-Oppenheimer dynamics”, where the nuclei respond to rapidly time-dependent force fields resulting from transient localization of the electrons. These real-time observations have spurred exciting new advances in the theoretical work to both explain and predict these novel dynamics. This book presents an overview of current theoretical work relevant to attosecond science written by theoreticians who are presently at the forefront of its development. It is a valuable reference work for anyone working in the field of attosecond science as well as those studying the subject.
Download or read book Springer Handbook of Atomic Molecular and Optical Physics written by Gordon W. F. Drake and published by Springer Nature. This book was released on 2023-02-09 with total page 1436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprises a comprehensive reference source that unifies the entire fields of atomic molecular and optical (AMO) physics, assembling the principal ideas, techniques and results of the field. 92 chapters written by about 120 authors present the principal ideas, techniques and results of the field, together with a guide to the primary research literature (carefully edited to ensure a uniform coverage and style, with extensive cross-references). Along with a summary of key ideas, techniques, and results, many chapters offer diagrams of apparatus, graphs, and tables of data. From atomic spectroscopy to applications in comets, one finds contributions from over 100 authors, all leaders in their respective disciplines. Substantially updated and expanded since the original 1996 edition, it now contains several entirely new chapters covering current areas of great research interest that barely existed in 1996, such as Bose-Einstein condensation, quantum information, and cosmological variations of the fundamental constants. A fully-searchable CD- ROM version of the contents accompanies the handbook.
Download or read book Nonadiabatic Transition written by Hiroki Nakamura and published by World Scientific. This book was released on 2012 with total page 515 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonadiabatic transition is a highly multidisciplinary concept and phenomenon, constituting a fundamental mechanism of state and phase changes in various dynamical processes of physics, chemistry and biology, such as molecular dynamics, energy relaxation, chemical reaction, and electron and proton transfer. Control of molecular processes by laser fields is also an example of time-dependent nonadiabatic transition. In this new edition, the original chapters are updated to facilitate enhanced understanding of the concept and applications. Three new chapters OCo comprehension of nonadiabatic chemical dynamics, control of chemical dynamics, and manifestation of molecular functions OCo are also added.
Download or read book The Theory of Chemical Reaction Dynamics written by D.C. Clary and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: The calculation of cross sections and rate constants for chemical reactions in the gas phase has long been a major problem in theoretical chemistry. The need for reliable and applicable theories in this field is evident when one considers the significant recent advances that have been made in developing experimental techniques, such as lasers and molecular beams, to probe the microscopic details of chemical reactions. For example, it is now becoming possible to measure cross sections for chemical reactions state selected in the vibrational rotational states of both reactants and products. Furthermore, in areas such as atmospheric, combustion and interstellar chemistry, there is an urgent need for reliable reaction rate constant data over a range of temperatures, and this information is often difficult to obtain in experiments. The classical trajectory method can be applied routinely to simple reactions, but this approach neglects important quantum mechanical effects such as tunnelling and resonances. For all these reasons, the quantum theory of reactive scattering is an area that has received considerable attention recently. This book describes the proceedings of a NATO Advanced Research Workshop held at CECAM, Orsay, France in June, 1985. The Workshop concentrated on a critical examination and discussion of the recent developments in the theory of chemical reaction dynamics, with particular emphasis on quantum theories. Several papers focus on exact theories for reactions.
Download or read book Selected Topics of the Theory of Chemical Elementary Processes written by E.E. Nikitin and published by Springer. This book was released on 1978-06 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction 1 1. 2. Basic Concepts and Phenomenological Description 6 2.1. Separation of the Center-of-Mass Motion 8 2.2. Separation of Electronic and Nuclear Motions. Interaction Potentials (Potential-Energy Surfaces) 11 2.2.1. Heuristic Considerations 11 2.2.2. Born-Oppenheimer Separation. Adiabatic Approximation, 16 Present State of Potential-Energy-Burface 2.2.3. Calculations 23 2.3. Scattering Channels ~6 2.4. Classification of Elementary Processes. Microscopic Mechanism 27 D.ynamics of Atomic and Molecular Collisions: 3. Electronically Adiabatic Processes 32 Classical Approach 3.1. 33 Some Arguments for the Reliability of the Classical Approach 33 Atom-Atom Collisions. Elastic Scattering 34 Quasiclassical Treatment of Elementary Processes in Triatomic Systems: Inelastic and Reactive Scattering 44 IV Examples of Results of Trajectory Calculations 59 3.1.4. 64 Elements of Quantum-Mechanical Methods 3.2. Correspondence of Classical and Quantum 3.2.1. 64 Mechanical Theories Time-Dependent Scattering Theory 71 3.2.2. Stationary Scattering Theory 77 3.2.3. One-Dimensional Scattering 78 3.2.3.1 • Three-Dimensional Elastic Scattering 83 3.2.3.2. Rearrangement Scattering (Reactions) 85 3.2.3.3. Examples of Quantum-Mechanical Calculations 3.2.4.
Download or read book Controlling Chemical Reactivities Beyond Existing Paradigms written by Xinyang Li and published by . This book was released on 2022 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Traditionally, there are two well-known ways to control chemical reactions, namely, thermodynamic control and kinetic control. However, recent experimental progress has demonstrated that there could be many other paradigms beyond these two textbook examples. For example, new experiments have demonstrated the quantum tunneling control for the reactivities, as well as the vibrational strong coupling (VSC) regime in polariton chemistry by coupling molecular vibrations with the quantized radiation mode inside an optical cavity. Nuclear quantum effects (NQEs), including quantum mechanical tunneling and the zero-point energy (ZPE), can play a vital role in certain chemical reactions. Although the quantum tunnel through a barrier has a well-known effect, the ability to use quantum tunneling to control the direction of a chemical reaction has only been recognized recently. A product that is neither favored kinetically nor thermodynamically can be formed through intrinsic quantum tunneling, without using any additional catalyst. This new strategy is referred to as tunneling control. Thus, it is essential to incorporate the NQEs in the study of tunneling-controlled chemical reactions. Polariton chemistry is an exciting emerging field on manipulating chemical reactivities using intrinsic quantum light-matter interactions. When an ensemble of molecules are put into an optical cavity (which is formed by having two reflecting mirrors), a set of new light-matter entangled states, so-called polaritons. The polariton states can be generated from the strong coupling between molecular vibrational excitations and photonic excitations, under the so-called VSC regime. It has been experimentally demonstrated that the cavity can modify the ground state reactivities under the VSC regime and change the selectivities among competing reaction pathways. This effect can potentially open up new possibilities for synthetic chemistry. However, a clear theoretical understanding of the fundamental mechanism remains elusive. To investigate the fundamental reactive mechanism behind these new paradigms, we use theoretical approaches and dynamics simulations to directly investigate these processes. The reaction rate constant can directly reflect the relative contribution of the quantum mechanical tunneling effects and capture dynamical effects that otherwise will not be included in the transition state theory (TST) rate constant. With the reaction rate theory, one can accurately calculate the chemical reaction rate constant through the molecular dynamics (MD) simulations and, therefore, provide new theoretical insights into tunneling controlled reactions and VSC polariton chemistry, both of which can potentially lead to new chemical reactivities. In this thesis, we have studied a tunneling-controlled reaction and the rate suppression originated from the light-matter interaction inside an optical cavity, through MD simulations and the Grote-Hynes (GH) theory. We have theoretically demonstrated that it is possible for tunneling to control the reaction directions and it is feasible as well to simulate tunneling-controlled reactions ab initio with NQEs included. For the VSC regime in polariton chemistry, we show that the resonant effects can arise from the non-Markovian nature of the cavity radiation mode, where the photons act like a solvent trapping the reactive molecules in the barrier region, hence slowing down the reaction rate"--Pages x-xi.
Download or read book Theory of Chemical Reaction Dynamics written by Antonio Laganà and published by Springer Science & Business Media. This book was released on 2005 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Chemical Reaction Dynamics written by Peter M. Rentzepis and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the formal lectures and contributed papers presented at the NATO Advanced Study Institute on. the Advances in Chemical Reaction Dynamics. The meeting convened at the city of Iraklion, Crete, Greece on 25 August 1985 and continued to 7 September 1985. The material presented describes the fundamental and recent advances in experimental and theoretical aspects of, reaction dynamics. A large section is devoted to electronically excited states, ionic species, and free radicals, relevant to chemical sys tems. In addition recent advances in gas phase polymerization, formation of clusters, and energy release processes in energetic materials were presented. Selected papers deal with topics such as the dynamics of electric field effects in low polar solutions, high electric field perturbations and relaxation of dipole equilibria, correlation in picosecond/laser pulse scattering, and applications to fast reaction dynamics. Picosecond transient Raman spectroscopy which has been used for the elucidation of reaction dynamics and structural changes occurring during the course of ultrafast chemical reactions; propagation of turbulent flames and detonations in gaseous· energetic systems are also discussed in some detail. In addition a large portion of the program was devoted to current experimental and theoretical studies of the structure of the transition state as inferred from product state distributions; translational energy release in the photodissociation of aromatic molecules; intramolecu lar and intraionic dynamic processes.
Download or read book Theoretical Studies of the Dynamics of Chemical Reactions written by Wei-Ping Hu and published by . This book was released on 1995 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Excursions in Chemical Dynamics written by Shervin Fatehi and published by . This book was released on 2010 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: As early as 1929, Dirac was sufficiently confident in the new quantum theory to assert that the physical laws underlying all chemistry were known; what remained, then, was to find tractable approximations within which to apply them. The most famous of these approximations, due to Born and Oppenheimer, partitions chemistry as formulated quantum mechanically into separate electronic and nuclear problems. While treatments of electronic structure within this framework are now routine among chemists, nuclei are still often treated classically. It is impossible, however, to be certain as to whether nuclear quantum effects will contribute to the physics of any given system. The present work addresses these effects at varying levels of approximation and in the context both of concrete systems (aqueous solutions and isolated molecules) and general methodology. After a brief introduction in Chapter 1, we proceed in Chapter 2 to discuss recent X-ray photoelectron spectra on aqueous hydroxide solutions, which were seen to exhibit the off-site Auger decay process known as intercoulombic decay (ICD). Arguments were made regarding the necessary conditions for ICD to occur -- specifically, that it would take place selectively along a hydrogen bond donated by the hydroxide ion. This mechanistic claim ties in with an ongoing controversy over the solvation structure of hydroxide and would constitute decisive evidence for the hypercoordinated model (which allows transient hydrogen bond donation by hydroxide) over the proton-hole model (which does not). We have performed X-ray absorption calculations using the eXcited electron and Core Hole (XCH) method that indicate that hydrogen-bond donation is not a prerequisite for ICD in this system. Additional calculations suggest that X-ray absorption techniques are also unlikely to be able to distinguish between the two solvation models. In reaching these conclusions, we stress that there are general theoretical criteria for the occurrence of ICD and suggest that they may be used predictively. We further propose that our criteria can be combined with the XCH method to aid in the rational design of a new type of chemo-/radio-therapy protocol for cancer treatment. In particular, we are preparing a proof-of-principle experiment on a model biological solution of bismuth, citrate, and urea. In Chapter 3, we address nuclear motion explicitly. Several models of the X-ray absorption spectrum of nitrogen gas (N2) are studied in the context of the standard Born-Oppenheimer approximation and XCH. Systematic improvements are made to an initially classical model that includes nuclear motion exactly, beginning with the substitution of the quantum mechanical nuclear density in the bond length R for its classical counterpart, followed by the addition of zero-point energy and other level-shifting effects, and finally the inclusion of explicit rovibrational quantization of both the ground and excited states. The quantization is determined exactly using the Colbert-Miller discrete variable representation (DVR), with further details provided in a pair of appendices. It is shown that the spectrum can be predicted semiquantitatively within this simple framework and that it compares respectably well with the prediction obtained using more accurate potentials. With respect to nuclear dynamics, the key lesson is that quantization of nuclear motion is absolutely essential if one wishes to capture fine structure in the spectrum; simpler approaches will, at best, properly reproduce a sharp absorption edge. In Chapter 4, we examine a method for the approximate inclusion of true dynamical effects associated with moment-to-moment nuclear motion. In particular, we study ring polymer molecular dynamics (RPMD), which (though developed recently) has already proven to be a useful theory for the calculation of a wide variety of properties of chemical systems. It is founded, however, on a heuristic extension of the rigorously-derived method of path integral molecular dynamics (PIMD). We attempt to derive the method by way of judicious approximations to exact expressions for the correlation function and, that failing, by "reverse engineering." These attempts do not succeed, in general, but may eventually provide a means of obtaining the method in the case of a harmonic oscillator, for which it is exact. At the very least, the expressions obtained offer further evidence that RPMD is a reasonable extension of rigorous methods.
Download or read book Chemical Reaction Theory written by Royal Society of Chemistry and published by Royal Society of Chemistry. This book was released on 1998 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt: Papers presenting the theory of chemical reactions and the comparison with experiment.
Download or read book Conical Intersections written by Wolfgang Domcke and published by World Scientific. This book was released on 2011 with total page 769 pages. Available in PDF, EPUB and Kindle. Book excerpt: The concept of adiabatic electronic potential-energy surfaces, defined by the Born?Oppenheimer approximation, is fundamental to our thinking about chemical processes. Recent computational as well as experimental studies have produced ample evidence that the so-called conical intersections of electronic energy surfaces, predicted by von Neumann and Wigner in 1929, are the rule rather than the exception in polyatomic molecules. It is nowadays increasingly recognized that conical intersections play a key mechanistic role in chemical reaction dynamics. This volume provides an up-to-date overview of the multi-faceted research on the role of conical intersections in photochemistry and photobiology, including basic theoretical concepts, novel computational strategies as well as innovative experiments. The contents and discussions will be of value to advanced students and researchers in photochemistry, molecular spectroscopy and related areas.
Download or read book Conical Intersections Electronic Structure Dynamics Spectroscopy written by Wolfgang Domcke and published by World Scientific. This book was released on 2004-07-14 with total page 857 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is widely recognized nowadays that conical intersections of molecular potential-energy surfaces play a key mechanistic role in the spectroscopy of polyatomic molecules, photochemistry and chemical kinetics. This invaluable book presents a systematic exposition of the current state of knowledge about conical intersections, which has been elaborated in research papers scattered throughout the chemical physics literature.Section I of the book provides a comprehensive analysis of the electronic-structure aspects of conical intersections. Section II shows the importance of conical intersections in chemical reaction dynamics and gives an overview of the computational techniques employed to describe the dynamics at conical intersections. Finally, Section III deals with the role of conical intersections in the fields of molecular spectroscopy and laser control of chemical reaction dynamics.This book has been selected for coverage in:• CC / Physical, Chemical & Earth Sciences• Chemistry Citation Index(tm)• Index to Scientific Book Contents® (ISBC)
Download or read book Beyond Born Oppenheimer written by Michael Baer and published by John Wiley & Sons. This book was released on 2006-03-31 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: INTRODUCING A POWERFUL APPROACH TO DEVELOPING RELIABLE QUANTUM MECHANICAL TREATMENTS OF A LARGE VARIETY OF PROCESSES IN MOLECULAR SYSTEMS. The Born-Oppenheimer approximation has been fundamental to calculation in molecular spectroscopy and molecular dynamics since the early days of quantum mechanics. This is despite well-established fact that it is often not valid due to conical intersections that give rise to strong nonadiabatic effects caused by singular nonadiabatic coupling terms (NACTs). In Beyond Born-Oppenheimer, Michael Baer, a leading authority on molecular scattering theory and electronic nonadiabatic processes, addresses this deficiency and introduces a rigorous approach--diabatization--for eliminating troublesome NACTs and deriving well-converged equations to treat the interactions within and between molecules. Concentrating on both the practical and theoretical aspects of electronic nonadiabatic transitions in molecules, Professor Baer uses a simple mathematical language to rigorously eliminate the singular NACTs and enable reliable calculations of spectroscopic and dynamical cross sections. He presents models of varying complexity to illustrate the validity of the theory and explores the significance of the study of NACTs and the relationship between molecular physics and other fields in physics, particularly electrodynamics. The first book of its king Beyond Born-Oppenheimer: * Presents a detailed mathematical framework to treat electronic NACTs and their conical intersections * Describes the Born-Oppenheimer treatment, including the concepts of adiabatic and diabatic frameworks * Introduces a field-theoretical approach to calculating NACTs, which offers an alternative to time-consuming ab initio procedures * Discusses various approximations for treating a large system of diabatic Schrödinger equations * Presents numerous exercises with solutions to further clarify the material being discussed Beyond Born-Oppenheimer is required reading for physicists, physical chemists, and all researchers involved in the quantum mechanical study of molecular systems.
Download or read book Molecular Quantum Dynamics written by Fabien Gatti and published by Springer Science & Business Media. This book was released on 2014-04-09 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on current applications of molecular quantum dynamics. Examples from all main subjects in the field, presented by the internationally renowned experts, illustrate the importance of the domain. Recent success in helping to understand experimental observations in fields like heterogeneous catalysis, photochemistry, reactive scattering, optical spectroscopy, or femto- and attosecond chemistry and spectroscopy underline that nuclear quantum mechanical effects affect many areas of chemical and physical research. In contrast to standard quantum chemistry calculations, where the nuclei are treated classically, molecular quantum dynamics can cover quantum mechanical effects in their motion. Many examples, ranging from fundamental to applied problems, are known today that are impacted by nuclear quantum mechanical effects, including phenomena like tunneling, zero point energy effects, or non-adiabatic transitions. Being important to correctly understand many observations in chemical, organic and biological systems, or for the understanding of molecular spectroscopy, the range of applications covered in this book comprises broad areas of science: from astrophysics and the physics and chemistry of the atmosphere, over elementary processes in chemistry, to biological processes (such as the first steps of photosynthesis or vision). Nevertheless, many researchers refrain from entering this domain. The book "Molecular Quantum Dynamics" offers them an accessible introduction. Although the calculation of large systems still presents a challenge - despite the considerable power of modern computers - new strategies have been developed to extend the studies to systems of increasing size. Such strategies are presented after a brief overview of the historical background. Strong emphasis is put on an educational presentation of the fundamental concepts, so that the reader can inform himself about the most important concepts, like eigenstates, wave packets, quantum mechanical resonances, entanglement, etc. The chosen examples highlight that high-level experiments and theory need to work closely together. This book thus is a must-read both for researchers working experimentally or theoretically in the concerned fields, and generally for anyone interested in the exciting world of molecular quantum dynamics.
