The Unitary Group in Quantum Chemistry

The Unitary Group in Quantum Chemistry PDF Author: Frederick Albert Matsen
Publisher: Elsevier Publishing Company
ISBN:
Category : Chemistry, Physical and theoretical
Languages : en
Pages : 416

Get Book Here

Book Description
A major concern of quantum chemistry is the prediction of properties of atoms and molecules. These predictions can be based on the solutions to certain theoretical equations. The solutions to equations for molecular systems are usually not exact. Approximate solutions therefore have to be obtained by the application of sophisticated mathematical techniques. The application of symmetry theory is essential in this process. Unitary groups arise from the application of this symmetry theory. This book concerns the use of the unitary group in such quantum chemistry calculations. The subject will be of interest to physicists and those chemists who have a strong mathematical leaning and who are developing methods for calculating molecular properties by quantum mechanical methods.

The Unitary Group in Quantum Chemistry

The Unitary Group in Quantum Chemistry PDF Author: Frederick Albert Matsen
Publisher: Elsevier Publishing Company
ISBN:
Category : Chemistry, Physical and theoretical
Languages : en
Pages : 416

Get Book Here

Book Description
A major concern of quantum chemistry is the prediction of properties of atoms and molecules. These predictions can be based on the solutions to certain theoretical equations. The solutions to equations for molecular systems are usually not exact. Approximate solutions therefore have to be obtained by the application of sophisticated mathematical techniques. The application of symmetry theory is essential in this process. Unitary groups arise from the application of this symmetry theory. This book concerns the use of the unitary group in such quantum chemistry calculations. The subject will be of interest to physicists and those chemists who have a strong mathematical leaning and who are developing methods for calculating molecular properties by quantum mechanical methods.

The Symmetric Group in Quantum Chemistry

The Symmetric Group in Quantum Chemistry PDF Author: R. Pauncz
Publisher: CRC Press
ISBN: 1351085670
Category : Science
Languages : en
Pages : 343

Get Book Here

Book Description
This is the first book to provide comprehensive treatment of the use of the symmetric group in quantum chemical structures of atoms, molecules, and solids. It begins with the conventional Slater determinant approach and proceeds to the basics of the symmetric group and the construction of spin eigenfunctions. The heart of the book is in the chapter dealing with spin-free quantum chemistry showing the great interpretation value of this method. The last three chapters include the unitary group approach, the symmetric group approach, and the spin-coupled valence bond method. An extensive bibliography concludes the book.

Horizons of Quantum Chemistry

Horizons of Quantum Chemistry PDF Author: K. Fukui
Publisher: Springer Science & Business Media
ISBN: 9400990278
Category : Science
Languages : en
Pages : 290

Get Book Here

Book Description
Proceedings of the Third International Congress of Quantum Chemistry, held at Kyoto, Japan, October 29-November 3, 1979

The Unitary Group for the Evaluation of Electronic Energy Matrix Elements

The Unitary Group for the Evaluation of Electronic Energy Matrix Elements PDF Author: Jürgen Hinze
Publisher: Springer Science & Business Media
ISBN: 3642931634
Category : Science
Languages : en
Pages : 381

Get Book Here

Book Description
During the last thirty years, with the development of high speed electronic computers, methods have evolved, which permit an accurate and quantitative, ab initio determina tion of the electronic wavefunctions of atoms and molecules. Thus a detailed elucida tion of the electronic energy and structure of molecules has become possible using quantum mechanics directly. Ho\~ever, it is necessary, if such calculations are to yield accurate and reliable results, to include electron correlation explicitely, which requires in general . configuration mixing procedures with an extremely large 5 number of configurations, of the order of 10 configurations. With eigenvalue problems of this size, the limits of even the largest and fastest computers are reached rapidly, and their solution has become possible only, because direct methods have been deve~ loped which permit the determination of eigenvalues and eigenvectors for such large matrices iteratively without constructing the energy matrix explicitely. These direct methods had been limited to the description of closed shell systems, i. e. systems with a single dominant closed shell reference determinant. This limitation arose, because with an open shell reference or with several reference determinants, no procedures were known, which allowed a rapid calculation of the energy matrix elements between configurations with general and widely different spin couplings, which would be necessary. Recently such methods have been developed, based on early work of Gelfand, Biedenharn and Moshinski using a unitary group representation of different spin coupled states; Paldus achieved an extremely compact description.

Advances in Quantum Chemistry

Advances in Quantum Chemistry PDF Author:
Publisher: Academic Press
ISBN: 0080582524
Category : Science
Languages : en
Pages : 422

Get Book Here

Book Description
Advances in Quantum Chemistry publishes surveys of current developments in the rapidly developing field of quantum chemistry--a 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, this quality serial provides a single vehicle for following progress in this interdisciplinary area.

Quantum Chemistry and Dynamics of Excited States

Quantum Chemistry and Dynamics of Excited States PDF Author: Leticia González
Publisher: John Wiley & Sons
ISBN: 1119417759
Category : Science
Languages : en
Pages : 52

Get Book Here

Book Description
An introduction to the rapidly evolving methodology of electronic excited states For academic researchers, postdocs, graduate and undergraduate students, Quantum Chemistry and Dynamics of Excited States: Methods and Applications reports the most updated and accurate theoretical techniques to treat electronic excited states. From methods to deal with stationary calculations through time-dependent simulations of molecular systems, this book serves as a guide for beginners in the field and knowledge seekers alike. Taking into account the most recent theory developments and representative applications, it also covers the often-overlooked gap between theoretical and computational chemistry. An excellent reference for both researchers and students, Excited States provides essential knowledge on quantum chemistry, an in-depth overview of the latest developments, and theoretical techniques around the properties and nonadiabatic dynamics of chemical systems. Readers will learn: ● Essential theoretical techniques to describe the properties and dynamics of chemical systems ● Electronic Structure methods for stationary calculations ● Methods for electronic excited states from both a quantum chemical and time-dependent point of view ● A breakdown of the most recent developments in the past 30 years For those searching for a better understanding of excited states as they relate to chemistry, biochemistry, industrial chemistry, and beyond, Quantum Chemistry and Dynamics of Excited States provides a solid education in the necessary foundations and important theories of excited states in photochemistry and ultrafast phenomena.

Spin Eigenfunctions

Spin Eigenfunctions PDF Author: Ruben Pauncz
Publisher: Springer Science & Business Media
ISBN: 1468485261
Category : Science
Languages : en
Pages : 374

Get Book Here

Book Description
The aim of this book is to give a comprehensive treatment of the different methods for the construction of spin eigenfunctions and to show their interrelations. The ultimate goal is the construction of an antisymmetric many-electron wave function that has both spatial and spin parts and the calculation of the matrix elements of the Hamiltonian over the total wave function. The representations of the symmetric group playa central role both in the construction of spin functions and in the calculation of the matrix elements of the Hamiltonian, so this subject will be treated in detail. We shall restrict the treatment to spin-independent Hamiltonians; in this case the spin does not have a direct role in the energy expression, but the choice of spin functions influences the form of spatial functions through the antisymmetry principle; the spatial functions determine the energy of the system. We shall also present the "spin-free quantum chemistry" approach of Matsen and co-workers, in which one starts immediately with the construction of spatial functions that have the correct permutational symmetries. By presenting both the conventional and the spin-free approach, one gains a better understanding of certain aspects of the elec tronic correlation problem. The latest advance in the calculation of the matrix elements of the Hamiltonian is the use of the representations of the unitary group, so this will be the last subject. It is a pleasant task to thank all those who helped in writing this book.

Quantum Chemistry and Dynamics of Excited States

Quantum Chemistry and Dynamics of Excited States PDF Author: Leticia González
Publisher: John Wiley & Sons
ISBN: 1119417724
Category : Science
Languages : en
Pages : 688

Get Book Here

Book Description
An introduction to the rapidly evolving methodology of electronic excited states For academic researchers, postdocs, graduate and undergraduate students, Quantum Chemistry and Dynamics of Excited States: Methods and Applications reports the most updated and accurate theoretical techniques to treat electronic excited states. From methods to deal with stationary calculations through time-dependent simulations of molecular systems, this book serves as a guide for beginners in the field and knowledge seekers alike. Taking into account the most recent theory developments and representative applications, it also covers the often-overlooked gap between theoretical and computational chemistry. An excellent reference for both researchers and students, Excited States provides essential knowledge on quantum chemistry, an in-depth overview of the latest developments, and theoretical techniques around the properties and nonadiabatic dynamics of chemical systems. Readers will learn: ● Essential theoretical techniques to describe the properties and dynamics of chemical systems ● Electronic Structure methods for stationary calculations ● Methods for electronic excited states from both a quantum chemical and time-dependent point of view ● A breakdown of the most recent developments in the past 30 years For those searching for a better understanding of excited states as they relate to chemistry, biochemistry, industrial chemistry, and beyond, Quantum Chemistry and Dynamics of Excited States provides a solid education in the necessary foundations and important theories of excited states in photochemistry and ultrafast phenomena.

Symmetries in Science II

Symmetries in Science II PDF Author: Bruno Gruber
Publisher: Springer Science & Business Media
ISBN: 1475714726
Category : Science
Languages : en
Pages : 590

Get Book Here

Book Description
The Symposium "Symmetries in Science II" was held at Southern Illinois University, Carbondale, during the period March 24-26, 1986, following the Einstein Centennial Symposium "Symmetries in Science" after a lapse of seven years. As it was the case for the original Symposium, the 1986 Symposium was truly interdisciplinary and truly international. I wish to thank all participants who made the. effort to come to Carbondale, Illinois, from allover the world. At this point I also wish to express my sincere thanks to Dr. Albert Somit, President of Southern Illinois University at Carbondale, and Dr. John C. Guyon, Vice President for Academic Affairs and Research at Southern Illinois University at Carbondale. Their generous support and encouragement was instrumental in getting the Symposium organized. In addition I wish to thank Associate Vice President Charles B. Klasek, Dr. Russell R. Dutcher, Dean of the College of Science, John H. Yopp, Associate Dean, College of Science, Dr. Subir K. Bose, Chairman of the Physics Department, Dr. James Tyrrell, Chairman of the Chemistry Department, Dr. Jared H. Dorn, Director of International Programs and Services, Dr. Rhonda Jo Vinson, Director of International and Economic Development, Dr. Tommy T. Dunagan, Vice President of Sigma Xi at Southern Illinois University, Dr. George Garoian, Professor of Zoology, Dr. Ann Phillippi, Assistant Professor of Zoology and Dr. Linda R. Gannon, Coordinator of Women's Studies, for their support and assistance.

Advanced Theories and Computational Approaches to the Electronic Structure of Molecules

Advanced Theories and Computational Approaches to the Electronic Structure of Molecules PDF Author: C.E. Dykstra
Publisher: Springer Science & Business Media
ISBN: 940096451X
Category : Science
Languages : en
Pages : 241

Get Book Here

Book Description
That there have been remarkable advances in the field of molecular electronic structure during the last decade is clear not only to those working in the field but also to anyone else who has used quantum chemical results to guide their own investiga tions. The progress in calculating the electronic structures of molecules has occurred through the truly ingenious theoretical and methodological developments that have made computationally tractable the underlying physics of electron distributions around a collection of nuclei. At the same time there has been consider able benefit from the great advances in computer technology. The growing sophistication, declining costs and increasing accessibi lity of computers have let theorists apply their methods to prob lems in virtually all areas of molecular science. Consequently, each year witnesses calculations on larger molecules than in the year before and calculations with greater accuracy and more com plete information on molecular properties. We can surely anticipate continued methodological develop ments of real consequence, and we can also see that the advance in computational capability is not about to slow down. The recent introduction of array processors, mUltiple processors and vector machines has yielded a tremendous acceleration of many types of computation, including operations typically performed in quantum chemical studies. Utilizing such new computing power to the ut most has required some new ideas and some reformulations of existing methods.