Background
Pauncz, Ruben Rezsö was born on August 8, 1920 in Szoreg, Hungary. Son of Ferenc and Sarolta (Popper) Pauncz.
(This is the first book to provide comprehensive treatment...)
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.
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(The aim of this book is to give a comprehensive treatment...)
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.
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(The author wrote a monograph 20 years ago on the construc...)
The author wrote a monograph 20 years ago on the construction of spin eigen functions; the monograph was published by Plenum. The aim of that mono graph was to present all aspects connected with the construction of spin eigen functions and its relation to the use of many-electron antisymmetric wavefunc tions. The present book is an introduction to these subjects, with an emphasis on the practical side. After the theoretical treatment, there will be many exam ples and exercises which will illustrate the different methods. The theory of the symmetric group and its representations generated by the different spin eigen functions is an other subject, this is closely related to the quantum chemical applications. Finally we will survey the calculation of the matrix elements of the Hamiltonian, using the different constructions of the spin functions. The closing chapter will deal with a new method that gained much importance recently; the spin-coupled valence bond method. Since the publication of Spin Eigenfunctions, nearly 20 years ago there have been many interesting developments in the subject; there are quite a few new algorithms for the construction of spin eigenfunctions. Moreover the use of the spin-coupled valence bond method showed the importance of using different constructions for the spin functions. The subject matter of this book has been presented in a graduate course in the Technion. The author is obliged to the graduate students Averbukh Vitali, Gokhberg Kirill, and Narevicius Edvardas for many helpful comments.
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(A major concern of quantum chemistry is the prediction of...)
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.
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Pauncz, Ruben Rezsö was born on August 8, 1920 in Szoreg, Hungary. Son of Ferenc and Sarolta (Popper) Pauncz.
Doctor of Philosophy, University Szeged, 1944. Doctorate (honorary), University Szeged, 1996.
Lecturer University Szeged, 1948-1956. Senior lecturer Technion, Haifa, Israel, 1956-1960, assistant professor Israel, 1960-1962, professor Israel, 1962-1988. Emeritus, since 1988.
(The aim of this book is to give a comprehensive treatment...)
(This is the first book to provide comprehensive treatment...)
(The author wrote a monograph 20 years ago on the construc...)
(A major concern of quantum chemistry is the prediction of...)
Member Israel Chemical Society (medal 2005), Royal Society Chemistry, Hungarian Academy of Sciences, International Academy Quantum Molecular Science, European Academy Arts, Sciences and Humanities.
Married Miriam Jakabovits, April 20, 1949 (deceased 1984). Children: Shmuel, Avraham. Married Kata Heller, October 24, 1985.