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We characterize an isolated molecule by its compos~t~on, i.e. the number and types of atoms forming the molecule, its structure, i.e. the geometrical arrangement of the composite atoms with respect to each other, and its possible, i.e. quantum mechanically allowed, stationary energy states. Conceptually we separate the latter, being aware that this is an approximation, into electronic, vibrational and rotational states, including fine and hyperfine structure splittings. To be sure, there is an intimate relation between molecular structure and molecular energy states, in fact it is this relation we use, when we obtain structural information through spectroscopy, where we determine transitions between various stationary states of the molecule. The concepts above have proven extremely useful in chemistry and spectroscopy, however, the awareness of the limitations of these concepts has grown in recent years with the increasing recognition of (i) fluctional molecules, (ii) multiphoton absorption processes and (iii) influences due to the surroundings on "isolated" molecules.
The NATO Advanced Study Institute (ASI) on "R@lativistic and Electron Correlation Effects in Molecules and Solids", co-sponsored by Simon Fraser University (SFU) and the Natural Sciences and Engineering Research Council of Canada (NSERC) was held Aug 10- 21, 1992 at the University of British Columbia (UBC), Vancouver, Canada. A total of 90 lecturers and students with backgrounds in Chemistry, Physics, Mathematics and various interdisciplinary subjects attended the ASI. In my proposal submitted to NATO for financial support for this ASI, I pointed out that a NATO ASI on the effects of relativity in many-electron systems was held ten years ago, [See G.L. Malli, (ed) Relativistic Effects in Atoms, Molecules and Solids, Plenum Press, Vol B87, New York, 1983]. Moreover, at a NATO Advanced Research Workshop (ARW) on advanced methods for molecular electronic structure "an assessment of state-of the-art of Electron Correlation ... " was carried out [see C.E. Dykstra, (ed), Advanced Theories and Computational Approaches to the Electronic Structure of Molecules, D. Reidel Publishin~ Company, Vol C133, Dordrecht, The Netherlands 1984]. However, during the last five years, it has become clear that the relativistic and electron correlation effects must be included in the theoretical treatment of many-electron molecules and solids of heavy elements (with Z > 70). Molecules and clusters containing heavy elements are of crucial importance in a number of areas of Chemistry and Physics such as nuclear fuels, catalysis, surface science, etc.
Excited States, Volume 5 consists of three concise and detailed chapters. These chapters cover the topics of excited-state potential surfaces of polyatomic molecules; vibronic spectroscopy of benzene; and quantum statistical mechanical (QSM) theory for molecular relaxation processes. Chapter 1 discusses excited-state potential surfaces with focus on ab initio calculations. Simple methods of computational schemes are also presented in this chapter. Chapter 2 reviews the excited electronic states of benzene. This chapter also includes the basic theory of benzene electronic excitations and the various types of spectroscopy (absorption, vibrational Raman, and electron-impact). Lastly, Chapter 3 presents a unified QSM theory, phenomenological theory of irreversible thermodynamics, and kinetics. The focus of QSM theory is on the nonlinear domain and is used to construct a nonlinear theory for the relaxation of excited molecules that are electric, vibrating, and rotating. This volume is a good reference for students and researchers studying in the field of chemistry and physics.
The Organic Chemist's Book of Orbitals focuses on the mechanisms, stereochemistry, and reactivity of molecular orbitals. Composed of four chapters, the book outlines how molecular orbitals are created by delocalization. Concerns include CC and CH single-bond orbitals; bond orbitals and group orbitals; and the localized orbitals of CH2 and CH3 groups. Schematic diagrams are presented to show the nature, reactions, and compositions of molecular orbitals. The text offers a list of molecules and orbital occupancies. Orbital drawings are presented to show the differences of the molecular orbitals of hydrogen, water, ammonia, methane, nitrogen, carbon monoxide, and acetylene. The book also provides an index of references for the molecular geometries and orbital energies employed in the orbital drawings. Considering the weight of data presented, the book is a great find for readers interested in studying molecular orbitals.
Organic materials with extraordinary magnetic properties promise a wide range of light, flexible, and inexpensive alternatives to familiar metal-based magnets. Individual organic molecules with high magnetic moments will be the foundation for design and fabrication of these materials. This book provides a systematic understanding of the structure and properties of organic magnetic molecules. After a summary of the phenomenon of magnetism at the molecular level, it presents a survey of the challenges to theoretical description and evaluation of the magnetic character of open-shell molecules, and an overview of recently developed methods and their successes and shortfalls. Several fields of application, including very strong organic molecular magnets and photo-magnetic switches, are surveyed. Finally, discussions on metal-based materials and simultaneously semiconducting and ferromagnetic extended systems and solids point the way toward future advances. The reader will find a comprehensive discourse on current understanding of magnetic molecules, a thorough survey of computational methods of characterizing known and imagined molecules, simple rules for design of larger magnetic systems, and a guide to opportunities for progress toward organic magnets.
The aim of this book Symmetry (Group Theory) and Mathematical Treatment in Chemistry is to be a graduate school-level text about introducing recent research examples associated with symmetry (group theory) and mathematical treatment in inorganic or organic chemistry, physical chemistry or chemical physics, and theoretical chemistry. Chapters contained can be classified into mini-review, tutorial review, or original research chapters of mathematical treatment in chemistry with brief explanation of related mathematical theories. Keywords are symmetry, group theory, crystallography, solid state, topology, molecular structure, electronic state, quantum chemistry, theoretical chemistry, and DFT calculations.