Friedhelm Bechstedt – författare

In recent decades, surface and interface physics has become an increasingly important subdiscipline within the physics of condensed matter as well as an interdisciplinary ?eld between physics, crystallography, chemistry, biology, and materials science. There are several driving forces for the development of the ?eld, among them semiconductor technology, new materials, epitaxy and chemical catalysis. The electrical and optical properties of nanostructures based on di?erent semiconductors are governed by the interfaces or, at least, by the presence of interfaces. A microscopic understanding of the growth processes requires the investigation of the surface processes at an atomic level. Elementary processes on surfaces, such as adsorption and desorption, play a key role in the understanding of heterogeneous catalysis. During the course of the surface investigations, it has been possible to observe a dramatic progress in the ability to study surfaces of materials in general, and on a microscopic scale in particular. There are two main reasons for this progress. From the experimental point of view it is largely due to the development and availability of new types of powerful microscopes. Sp- tacular advances in techniques such as scanning tunneling microscopy now allow us to observe individual atoms on surfaces, and to follow their paths with a clarity unimaginable a few years ago. From the theoretical point of view (or rather the viewpoint of simulation) progress is related to the wide availability of computers and the dramatic increase of their power.

In recent decades, surface and interface physics has become an increasingly important subdiscipline within the physics of condensed matter as well as an interdisciplinary ?eld between physics, crystallography, chemistry, biology, and materials science. There are several driving forces for the development of the ?eld, among them semiconductor technology, new materials, epitaxy and chemical catalysis. The electrical and optical properties of nanostructures based on di?erent semiconductors are governed by the interfaces or, at least, by the presence of interfaces. A microscopic understanding of the growth processes requires the investigation of the surface processes at an atomic level. Elementary processes on surfaces, such as adsorption and desorption, play a key role in the understanding of heterogeneous catalysis. During the course of the surface investigations, it has been possible to observe a dramatic progress in the ability to study surfaces of materials in general, and on a microscopic scale in particular. There are two main reasons for this progress. From the experimental point of view it is largely due to the development and availability of new types of powerful microscopes. Sp- tacular advances in techniques such as scanning tunneling microscopy now allow us to observe individual atoms on surfaces, and to follow their paths with a clarity unimaginable a few years ago. From the theoretical point of view (or rather the viewpoint of simulation) progress is related to the wide availability of computers and the dramatic increase of their power.

In recent decades, surface and interface physics has become an increasingly important subdiscipline within the physics of condensed matter as well as an interdisciplinary ?eld between physics, crystallography, chemistry, biology, and materials science. There are several driving forces for the development of the ?eld, among them semiconductor technology, new materials, epitaxy and chemical catalysis. The electrical and optical properties of nanostructures based on di?erent semiconductors are governed by the interfaces or, at least, by the presence of interfaces. A microscopic understanding of the growth processes requires the investigation of the surface processes at an atomic level. Elementary processes on surfaces, such as adsorption and desorption, play a key role in the understanding of heterogeneous catalysis. During the course of the surface investigations, it has been possible to observe a dramatic progress in the ability to study surfaces of materials in general, and on a microscopic scale in particular. There are two main reasons for this progress. From the experimental point of view it is largely due to the development and availability of new types of powerful microscopes. Sp- tacular advances in techniques such as scanning tunneling microscopy now allow us to observe individual atoms on surfaces, and to follow their paths with a clarity unimaginable a few years ago. From the theoretical point of view (or rather the viewpoint of simulation) progress is related to the wide availability of computers and the dramatic increase of their power.

The many-body-theoretical basis and applications of theoretical spectroscopy of condensed matter, e.g. crystals, nanosystems, and molecules are unified in one advanced text for readers from graduate students to active researchers in the field. The theory is developed from first principles including fully the electron-electron interaction and spin interactions. It is based on the many-body perturbation theory, a quantum-field-theoretical description, and Green's functions. The important expressions for ground states as well as electronic single-particle and pair excitations are explained. Based on single-particle and two-particle Green's functions, the Dyson and Bethe-Salpeter equations are derived. They are applied to calculate spectral and response functions. Important spectra are those which can be measured using photoemission/inverse photoemission, optical spectroscopy, and electron energy loss/inelastic X-ray spectroscopy. Important approximations are derived and discussed in the light of selected computational and experimental results. Some numerical implementations available in well-known computer codes are critically discussed. The book is divided into four parts: (i) In the first part the many-electron systems are described in the framework of the quantum-field theory. The electron spin and the spin-orbit interaction are taken into account. Sum rules are derived. (ii) The second part is mainly related to the ground state of electronic systems. The total energy is treated within the density functional theory. The most important approximations for exchange and correlation are delighted. (iii) The third part is essentially devoted to the description of charged electronic excitations such as electrons and holes. Central approximations as Hedin's GW and the T-matrix approximation are discussed.(iv) The fourth part is focused on response functions measured in optical and loss spectroscopies and neutral pair or collective excitations.

The many-body-theoretical basis and applications of theoretical spectroscopy of condensed matter, e.g. crystals, nanosystems, and molecules are unified in one advanced text for readers from graduate students to active researchers in the field. The theory is developed from first principles including fully the electron-electron interaction and spin interactions. It is based on the many-body perturbation theory, a quantum-field-theoretical description, and Green''s functions. The important expressions for ground states as well as electronic single-particle and pair excitations are explained. Based on single-particle and two-particle Green''s functions, the Dyson and Bethe-Salpeter equations are derived. They are applied to calculate spectral and response functions. Important spectra are those which can be measured using photoemission/inverse photoemission, optical spectroscopy, and electron energy loss/inelastic X-ray spectroscopy. Important approximations are derived and discussed in the light of selected computational and experimental results. Some numerical implementations available in well-known computer codes are critically discussed. The book is divided into four parts: (i) In the first part the many-electron systems are described in the framework of the quantum-field theory. The electron spin and the spin-orbit interaction are taken into account. Sum rules are derived. (ii) The second part is mainly related to the ground state of electronic systems. The total energy is treated within the density functional theory. The most important approximations for exchange and correlation are delighted. (iii) The third part is essentially devoted to the description of charged electronic excitations such as electrons and holes. Central approximations as Hedin''s GW and the T-matrix approximation are discussed.(iv) The fourth part is focused on response functions measured in optical and loss spectroscopies and neutral pair or collective excitations.