A Festschrift in honor of Professor Marvin L. Cohen This volume is a Festschrift in honor of Professor Marvin L. Cohen. The articles, contributed by leading researchers in condensed matter physics, high-light recent advances in the use of quantum theory to explain and predict properties of real materials. The invention of quantum mechanics in the 1920's provided detailed descriptions of the electronic structure of atoms. However, a similar understanding of solids has been achieved only in the past 30 years, owing to the complex electron-ion and electron electron interactions in these systems. Professor Cohen is a central figure in this achievement. His development of the pseudopotential and total energy methods provided an alternate route using computers for the exploration of solids and new materials even when they have not yet been synthesized. Professor Cohen's contributions to materials theory have been both fundamental and encompassing. The corpus of his work consists of over 500 papers and a textbook. His band structures for semiconductors are used worldwide by researchers in solid state physics and chemistry and by device engineers. Professor Cohen's own use of his theories has resulted in the determination of the electronic structure, optical properties, structural and vibrational properties, and superconducting properties of numerous condensed matter systems including semiconductors, metals, surfaces, interfaces, defects in solids, clusters, and novel materials such as the fullerides and nanotubes."

Modem materials science is exploiting novel tools of solid-state physics and chemistry to obtain an unprecedented understanding of the structure of matter at the atomic level. The direct outcome of this understanding is the ability to design and fabricate new materials whose properties are tailored to a given device ap plication. Although applications of materials science can range from low weight, high strength composites for the automobile and aviation industry to biocompat ible polymers, in no other field has progress been more strikingly rapid than in that of electronic materials. In this area, it is now possible to predict from first principles the properties of hypothetical materials and to construct artificially structured materials with layer-by-Iayer control of composition and microstruc ture. The resulting superlattices, multiple quantum wells, and high temperature superconductors, among others, will dominate our technological future. A large fraction of the current undergraduate and graduate students in science and engi neering will be directly involved in furthering the revolution in electronic mate rials. With this book, we want to welcome such students to electronic materials research and provide them with an introduction to this exciting and rapidly de veloping area of study. A second purpose of this volume is to provide experts in other fields of solid state physics and chemistry with an overview of contemporary research within the field of electronic materials."

A Festschrift in honor of Professor Marvin L. Cohen This volume is a Festschrift in honor of Professor Marvin L. Cohen. The articles, contributed by leading researchers in condensed matter physics, high-light recent advances in the use of quantum theory to explain and predict properties of real materials. The invention of quantum mechanics in the 1920's provided detailed descriptions of the electronic structure of atoms. However, a similar understanding of solids has been achieved only in the past 30 years, owing to the complex electron-ion and electron electron interactions in these systems. Professor Cohen is a central figure in this achievement. His development of the pseudopotential and total energy methods provided an alternate route using computers for the exploration of solids and new materials even when they have not yet been synthesized. Professor Cohen's contributions to materials theory have been both fundamental and encompassing. The corpus of his work consists of over 500 papers and a textbook. His band structures for semiconductors are used worldwide by researchers in solid state physics and chemistry and by device engineers. Professor Cohen's own use of his theories has resulted in the determination of the electronic structure, optical properties, structural and vibrational properties, and superconducting properties of numerous condensed matter systems including semiconductors, metals, surfaces, interfaces, defects in solids, clusters, and novel materials such as the fullerides and nanotubes."

We began planning and writing this book in thc late 1970$ at thc ugge s stion of Manuel Cardona and Helmut Latsch. We also received considerable eo couragement and stimulation from colleagues. Same said there was a need for instructional material in tbis area while others emphasized thc utility of a research text. We tried to strike a compromise. Thc figures, tables, and rcferences are included to enable researchcrs to obt81o quickly essential information in this area of semiconductor research. For instructoTS and stu dents, we attempt to cover same basic ideas abaut electronic structure and semiconductor physics with applications to real, rather than model, solids. Ve \Vish to thank our colleagues and collaborators whose research rc sults and ideas are presented here. Special thanks are duc to Jim Phillips who illfluellced lIS hoth during ollr formative )'ears and afterwards. We are grateful to Sari Yamagishi for her patience and skill with the typing and production of the manuscript. Finally, we acknowledge the great patience of Helmut Lotsch and Manucl Cardona. llerkeley, CA M.L. Gehen . inncapolis, MN, J.R, Chelikew"ky March 1988 VII Contents 1. Introduction 1 2. Theoretical Concepts and Methods .................... . 4 2.1 Thc One-Electron Model and Band Structure 7 2.2 Properties cf En(k) ......................... . 11 3. Pseudopotentials 16 3.1 The Empirical Pseudopotential Method .......... 20 3.2 Self-Consistent and Ab Initio Pseudopotentials ...... ..... 25 4. Response Functiolls and Density of States . .."