Aspects Of Polaron Theory

This book follows a step-by-step approach, from comparatively simple physical ideas to a clear understanding of sophisticated mathematical tools of investigation in modern polaron physics. The reader is able to compare the physical point of view with methods proposed in the book, and at the same time grasp the underlying mathematics.

This monograph is an amplification of a set of special lectures delivered by the authors in the Physics Department of Moscow State University. The linear polaron model is studied. It is shown that the system is soluble for arbitrary coupling interaction strength between the electron and lattice vibrations. Detailed calculational techniques for obtaining the correlation, spectral and Green functions are given. The thermodynamic properties of the system are studied within the framework of the functional method.

The linear polaron model is an excellent example of an exactly soluble, yet nontrivial polaron system. It serves as a trial system or zero-level approximation in many sophisticated methods of polaron investigation. This book analyzes, in particular, the possibility of reduction of the full polaron Hamiltonian to the linear one, and introduces a special method of calculating thermodynamical characteristics based on the calculation of the averages of T-products. This T-product formalism seems to be a more convenient way of doing similar calculations involving Feynman's path integral approach.This book follows a step-by-step approach, from comparatively simple physical ideas to a clear understanding of sophisticated mathematical tools of investigation in modern polaron physics. The reader is able to compare the physical point of view with methods proposed in the book, and at the same time grasp the underlying mathematics.Some familiarity with quantum statistical mechanics is desirable in reading this book.

This monograph is an amplification of a set of special lectures delivered by the authors in the Physics Department of Moscow State University. The linear polaron model is studied. It is shown that the system is soluble for arbitrary coupling interaction strength between the electron and lattice vibrations. Detailed calculational techniques for obtaining the correlation, spectral and Green functions are given. The thermodynamic properties of the system are studied within the framework of the functional method.

This monograph is an amplification of a set of special lectures delivered by the authors in the Physics Department of Moscow State University. The linear polaron model is studied. It is shown that the system is soluble for arbitrary coupling interaction strength between the electron and lattice vibrations. Detailed calculational techniques for obtaining the correlation, spectral and Green functions are given. The thermodynamic properties of the system are studied within the framework of the functional method.

The book presents the development of the polaron theory and its applications in various fields of physics. Nowadays, methods of the polaron theory are widely used in such sciences as solid state and nuclear physics, chemistry, etc. The monograph includes selected articles, based on the talks, given at the Workshops held in Pushchino in 1993 and 1994. These articles cover different aspects of polaron physics and quantum field theory ranging from nuclear physics to solid state physics and chemistry, they involve both the fundamental research such as bipolarons and the polaron applications to study the self-trapped electron state in various liquids. We hope our book will be of interest to a broad range of readers, which can be able to sense the excitement of the articles.

Beginning with an introduction to the T-product approach in the theory of a particle interacting with bosonic fields as applied, for example, to the linearized polaron model, the book goes on to deal with the equilibrium state objective being to derive Bogolubov's inequality for the reduced free energy of the polaron. The third chapter deals with some problems related to the non-equilibrium polaron theory, including polaron kinetics. Finally, alternative methods used in polaron theory are also presented and compared with Bogolubov's method.