Computational Chemistry: Reviews Of Current Trends – serie

Vast progress in the area of computational chemistry has been achieved in the last decade. Theoretical methods such as quantum mechanics, molecular dynamics and statistical mechanics have been successfully used to characterize chemical systems and to design new materials, drugs and chemicals. The reviews presented in this volume discuss the current advances in computational methodologies and their applications. The areas covered include materials science, nanotechnology, inorganic and biological systems. The major thrust of the book is to bring timely overviews of new findings and methods applied in the rapidly changing field of computational chemistry.

This book presents an overview of recent progress in computational techniques as well as examples of the application of existing computational methods in different areas of chemistry, physics, and biochemistry. Introductory chapters cover a broad range of fundamental topics, including: state-of-the-art basis set expansion methods for computing atomic and molecular electronic structures based on the use of relativistic quantum mechanics; the most recent developments in Hartree-Fock methods, particularly in techniques suited for very large systems; the current analysis of the solute-solvent free energy of interaction and the physical bases used to evaluate the electrostatic, cavitation, and dispersion terms; an introduction to the additive fuzzy electron density fragmentation scheme within various ab initio Hartree-Fock quantum-chemical computational schemes, which has provided the means for generating representative molecular fragment densities characteristic to their local environment within a molecule. This book also features a review of recent ab initio calculations on the structure and interactions of DNA bases, a chapter on computational approaches to the design of safer drugs and their molecular properties, and a systematic conceptual study on a route which allows one to stuff fullerenes.

The contributions collected in this volume complement volume 1 of this series, disclosing results of current developments in methodologies and applications of computational chemistry methods. The covered topics include fundamentals and applications of propagator calculations, as well as recent developments in the computationally efficient and accurate SAC-CI method, which allows calculation of various electronic states at the same time. SAC-CI studies of excited states of large molecular systems like porphyrins are reviewed, and its application to investigations of surface phenomena is discussed. The book also features a review of recent work on quantum Monte Carlo simulations.Furthermore, the book discusses the application of computational methods to biomolecules and, in particular, the application of the DFT methods to prediction of molecular structures and the IR spectrum of the DNA bases, as well as currently developed force field parameters and their application in molecular dynamics calculations of biologically important molecules. Lastly, there is a review of a quantum chemistry course which prepares students at the Department of Chemistry of ETH Zurich to perform their own ab initio studies.

Volume 3 of Computational Chemistry: Reviews of Current Trends adds well to the first two volumes of the series, presenting results of current developments in the methodologies and the applications of computational chemistry methods. The topics covered include fundamentals and applications of multireference Brillouin-Wigner coupled-cluster theory, as well as recent developments in quantum-chemical modeling of the interaction of solute and solvent.The book also features a review of recent developments and applications of the model-core-potential method. The application of computational methods to gas-phase chemical reactions is discussed. In particular, stratospheric bromine chemistry and its relationship to depletion of stratospheric ozone is examined by theoretical methods. Also, fundamental phenomena of bonding in gas-phase radical-sulfur compounds are presented.Finally, the book gives a review of a hot area — chemistry on the Internet. In addition to a survey of relevant chemistry Internet resources, an overview of the current state of Internet application is provided.

This volume presents a balanced blend of methodological and applied contributions. It supplements well the first three volumes of the series, revealing results of current research in computational chemistry. It also reviews the topographical features of several molecular scalar fields. A brief discussion of topographical concepts is followed by examples of their application to several branches of chemistry.The size of a basis set applied in a calculation determines the amount of computer resources necessary for a particular task. The details of a common strategy — the ab initio model potential method — which could be used to minimize such a task are revealed in the subsequent contribution. Such an approach is applied to atoms, molecules and solids. Two chapters are devoted to the prediction of solvent effects in biological systems. These effects are significant for interactions of nucleic acid bases and crucial for an evaluation of the free energies that govern the associations of macromolecules in aqueous solutions.A chapter on the developments and applications of the multireference Moller-Plesset method could be used as a reference in theoretical studies of systems where both the dynamical and nondynamical correlation effects should be accounted for. This technique is an efficient tool in such investigations. An explosive application of computational techniques — studies of detonation initiation and sensitivity in energetic compounds — is discussed in detail in the last chapter. The computational treatment of such unstable compounds allows the prediction of their crucial properties without being subject to their destructive forces.

This volume comprises six chapters which explore the development and applications of the methods of computational chemistry. The first chapter is on new developments in coupled-cluster (CC) theory. The homotopy method is used to obtain complete sets of solutions of nonlinear CC equations. The correspondence between multiple solutions to the CCSD, CCSDT, and full CI equations is established, and the applications of the new approach in modeling molecular systems are discussed. The second chapter reviews the computational theory for the time-dependent calculations of a solution to the Schrödinger equation for two electrons and focuses on the development of propagators to the solution.The next chapter features a discussion on a new self-consistent field for molecular interactions (SCF-MI) scheme for modifying Roothaan equations in order to avoid basis set superposition errors (BSSE). This method is especially suitable for computations of intermolecular interactions. Details of the theory, along with examples of applications to nucleic acid base pair complexes, are given. This chapter is well complemented by the following chapter, which reports the current status of computational studies of aromatic stacking and hydrogen bonding interactions among nucleic acid bases. The next chapter reveals the possibility of calculating the kinetics of chemical reactions in biological systems from the first principles. The last chapter reviews the results of rigorous ab initio studies of the series of derivatives of methane, silane, and germane. The presented molecular and vibrational parameters complement experimental data for these systems. In addition, the theoretical approach allows the prediction of the effects of halogeno-substitutions on their structures and properties.

There are strong indications that, in the 21st century, computational chemistry will be a prime research tool not only for the basic sciences but also for the life and materials sciences. Recent developments in nanotechnology allow us to detect a layer of single atoms. Researchers are able not only to image but also to manipulate molecules and atoms. It does not take much imagination to realize that before performing such a task on a real system it is much easier and faster to study models on computers. That is the aim of this volume — it provides up-to-date reviews which cover representative areas of computational chemistry.In Chapter 1, Y Ishikawa and M J Vilkas provide a review of multireference Moller-Plesset (MR-MP) perturbation theory. Fifteen years ago Roberto Car of Princeton University and Michele Parrinello of Max Planck Institute introduced a method that revolutionized electronic structure calculations for molecules, liquids and solids. Ursula Rothlisberger, a former member of Parrinello's group, reviews the formation of the method in its most common implementations in Chapter 2. In the third chapter, Isaac B Bersuker describes the general theory of the combined quantum mechanics-molecular mechanics (QM/MM) approach. In Chapter 4, Marcel Allavena and David White present a review of applications of computational chemistry to proton transfer, the primary process for acid-base chemistry on zeolites. Chapter 5 is a review by S Roszak and J Leszczynski of recent data on the clusters formed from the charged ion and weakly interacting ligands. The last chapter, contributed by Carlos R Handy, is devoted to recent developments in the incorporation of continuous wavelet transform analysis into quantum operator theory.

Vast progress in the area of computational chemistry has been achieved in the last decade of the 20th century. Theoretical methods such as quantum mechanics, molecular dynamics and statistical mechanics have been successfully used to characterize chemical systems and to design new materials, drugs and chemicals. With this in mind, the contributions to this volume were collected.The contributions include predictions of the transport properties of molecular structures at the atomic level, which is of importance in solving crucial technological problems such as electromigration or temperature and statistical effects.Although currently restricted to calculation of systems containing no more than a few thousand atoms, nonempirical (ab initio) quantum chemical methods are quickly gaining popularity among researchers investigating various aspects of biological systems. The development of efficient methods for application to large molecular systems is the focus of two chapters. They include an overview of development and applications of parallel and order-N Density Functional Theory (DFT) methods and the development of new methods for calculation of electron dynamical correlation for large molecular systems.For small and medium-sized molecules, chemical accuracy of quantum chemical predictions has already been achieved in many fields of application. Among the most accurate methods are Coupled Cluster (CC) approaches, but their accuracy comes at a price — such methodologies are among the most computationally demanding. Two chapters review approximate strategies developed to include triple excitations within the coupled cluster and the performance of the explicitly correlated CC method based on the so-called R12 ansatz.The Quantum Molecular Dynamics (QMD) approach has revolutionized electronic structure calculations for molecular reactions. The last chapter of the volume provides details of QMD studies on interconversion of nitronium ions and nitric acid in small water clusters.

The gap between experimental objects and models for calculations in chemistry is being bridged. The size of experimental nano-objects is decreasing, while reliable calculations are feasible for larger and larger molecular systems. The results of these calculations for isolated molecules are becoming more relevant for experiments. However, there are still significant challenges for computational methods. This series of books presents reviews of current advances in computational methodologies and applications.Chapter 1 of this volume provides an overview of the theoretical and numerical aspects in the development of the polarizable continuum model (PCM). Chapter 2 demonstrates a multiplicative scheme used to estimate the properties of two- and three-dimensional clusters from the properties of their one-dimensional components. Chapter 3 discusses the application of ab initio methods for a reliable evaluation of the characteristics of hydrogen-bonded and van der Waals complexes.Ab initio quantum-chemical methods are popular among researchers investigating various aspects of DNA. The properties of DNA base polyads linked by base-base hydrogen bonds are reviewed in Chapter 4, while Chapter 5 reviews the primary radiation-induced defects in nucleic acid building blocks, and how DNA can be influenced by chemical and environmental effects. Finally, Chapter 6 discusses available experimental data of DNA bases, base pairs, and their complexes with water.