Advances In Quantum Chemical Bonding Structures

Chemical bond stands as the alpha-and-omega of Chemistry: it is at the beginning because, according with International Union of Pure and Applied Chemistry-IUPAC, a bond exists between two atoms or groups of atoms when the forces acting between them lead to an aggregation with sufficient stability to be considered as molecular species; it is also at the end due its mysterious way of acting through electronic behavior that is comparable with nothing of the observed world. The fact that two electrons, which in principle repel each other as they approach, can exist in a certain molecular space providing the atoms-in-molecule binding - that is still an unfolded reality. Nevertheless, quantum theory had furnished the main analytical tools with which the so called ordinary chemistry reduced at the many-electronic problem, a field equally belonging to quantum physics and quantum chemistry. After the impressive success of quantum theory in explaining atomic structure and spectra starting from the complete analytical solution of Hydrogen atom, and after the further quantum extensions of models to include the elucidation of simple molecules, the Chemistry arrives today in front of new challenges: nano- and bio-systems. At this point it seems that there is no chance to provide fully analytical results with the myriads of electrons in macro-molecules. Moreover, even one could admit that the computational techniques will evolve sufficient to deliver numerical results these will certainly suffer of opacity in interpretation loosing the most beloved issue of chemists: the intuition. At the same time, there are also relatively small molecules with particular bonding features, since bonds in which there are no shared electrons between atoms - at one extreme - or molecules with a sextuple bond - at other extreme - may be identified. As a consequence, the increased need of molecular design for assessing nano- and bio- targets through active ligands, the practical demands of predictions of acute toxicity in medicine and ecotoxicology - all these actual realities of chemistry in its principles and applications, call for dedicated reviews. In such theoretically demanded context of conceptual and computational chemistry the present review book likes to give a survey of the quantum physical chemistry and of its application in chemical bond and bonding description. Through the chapters of this book ones of the leading scientists in both physical and chemical fields have gave their valuable contributions for decrypting the actual status quo of the chemical bond and bonding: from self-consistent equations of many-electronic systems, localization, and reactivity principles, to coherent electronic states, to non-covalent bonding and overlapping concepts, to hydrogen and biomolecular bonding, to molecular connectivity and topological indices, to oscillatory quantum states of molecules, to carbon and pseudohalide bonding, to three-center bonding problem, to biochemistry, to medicine, and to ecotoxicology chemical bonding implications. It is therefore a comprehensive volume of physical and chemical quantum approaches of molecules grasping various conceptual and computational levels. It is also an invitation to reflect upon the possibility of unifying the physical and chemical quantum concepts in a novel alchemy of molecular structure. In this respect worth, finally, recalling that the author of Philosophia Naturalis Principia Mathematica was, at his time, proudly considered himself merely as an alchemist, and that his corpuscular vision about light was based on revealed concept of sympathy . From sympathy to bond and bonding it appears that the actual Chemistry and Physics continue to offer fascinating mysteries to humankind of which the elucidation of the nature of the chemical bond being, perhaps, the greatest one.

The concept of a chemical bond evolved from a variety of experimental observations. It became useful to understand, at times even predict, the molecular structure, reactivity and mechanism of chemical reactions. Every aspect of the concept of bonding received a quantitative interpretation from the advent of quantum mechanics and its application to chemistry.In Lectures on Chemical Bonding and Quantum Chemistry the reader will find a comprehensive discourse on the basic interpretation of the chemical bond as well as current understanding in terms of a 'dancing' molecule that not only travels, rotates and pulsates around an equilibrium molecular structure, but also interacts and collides with other molecules, thereby transferring linear and angular momentum characteristics and adjusting total energies. One will also find a thorough survey of quantum mechanical methodologies for calculation of molecular characteristics in specific states and their changes under spectroscopic transitions, tunneling, electron and proton transfer phenomena, and so on. Guides to more advanced levels of theory are also provided.

Advances in the Theory of Atomic and Molecular Systems, is a collection of contributions presenting recent theoretical and computational developments that provide new insights into the structure, properties, and behavior of a variety of atomic and molecular systems. This volume (subtitled: Conceptual and Computational Advances in Quantum Chemistry) focuses on electronic structure theory and its foundations. This volume is an invaluable resource for faculty, graduate students, and researchers interested in theoretical and computational chemistry and physics, physical chemistry and chemical physics, molecular spectroscopy, and related areas of science and engineering.

Advances in Quantum Chemical Topology Beyond QTAIM provides a complete overview of the field, starting with traditional methods and then covering key steps to the latest state-of-the-art extensions of QTAIM. The book supports researchers by compiling and reviewing key methods, comparing different algorithms, and providing computational results to show the efficacy of the approaches. Beginning with an introduction to quantum chemistry, QTAIM and key extensions, the book goes on to discuss interacting quantum atoms and related energy properties, explores partitioning methods, and compares algorithms for QTAIM. Partitioning schemes are them compared in more detail before applications are explored and future developments discussed. Drawing together the knowledge of key authorities in the area, this book provides a comprehensive, pedogeological guide to this insightful theory for all those interested in modelling, exploring and understanding molecular properties. Provides a contemporary review of the extensions and application of QTAIM methods Compiles all extensions of QTAIM in one place for easy reference Includes a chapter with an Introduction to Quantum Chemistry Presents complex information at a level accessible to those engaged in theoretical/computational chemistry

Advances in Quantum Chemistry publishes articles and invited reviews by leading international researchers in quantum chemistry. Quantum chemistry deals particularly with the electronic structure of atoms, molecules, and crystalline matter and describes it in terms of electron wave patterns. It uses physical and chemical insight, sophisticated mathematics and high-speed computers to solve the wave equations and achieve its results. Advances highlights these important, interdisciplinary developments.

Advances in Quantum Chemistry presents surveys of current developments in this rapidly developing field that falls between the historically established areas of mathematics, physics, chemistry, and biology. With invited reviews written by leading international researchers, each presenting new results, it provides a single vehicle for following progress in this interdisciplinary area. This volume concerns the proceedings of the 4th International Conference on the DV-Xá Method. The focus is on key issues of materials science, surfaces, boundaries, defects, metals, ceramics and organic materials and spectroscopy. The DV-Xá method is a Density Functional-like development, which has reached an unparalleled theoretical and practical sophistication in Japan and Korea. Publishes articles, invited reviews and proceedings of major international conferences and workshops Written by leading international researchers in quantum and theoretical chemistry Highlights important interdisciplinary developments

Advances in Quantum Chemistry presents surveys of current developments in this rapidly developing field that falls between the historically established areas of mathematics, physics, chemistry, and biology. With invited reviews written by leading international researchers, each presenting new results, it provides a single vehicle for following progress in this interdisciplinary area.

Advances in the Theory of Quantum Systems in Chemistry and Physics is a collection of 32 selected papers from the scientific contributions presented at the 15th International Workshop on Quantum Systems in Chemistry and Physics (QSCP-XV), held at Magdalene College, Cambridge, UK, from August 31st to September 5th, 2010. This volume discusses the state of the art, new trends, and the future of methods in molecular quantum mechanics and their applications to a wide range of problems in chemistry, physics, and biology. The breadth and depth of the scientific topics discussed during QSCP-XV are gathered in seven sections: I. Fundamental Theory; II. Model Atoms; III. Atoms and Molecules with Exponential-Type Orbitals; IV. Density-Oriented Methods; V. Dynamics and Quantum Monte-Carlo Methodology; VI. Structure and Reactivity; VII. Complex Systems, Solids, Biophysics. Advances in the Theory of Quantum Systems in Chemistry and Physics is written for research students and professionals in Quantum systems of chemistry and physics. It also constitutes and invaluable guide for those wishing to familiarize themselves with research perspectives in the domain of quantum systems for thematic conversion or simply to gain insight into the methodological developments and applications to physics chemistry and biology that have actually become feasible by the end of 2010.