Solids and Surfaces

A Chemist's View of Bonding in Extended Structures

Roald Hoffmann

• Publisher: Wiley-VCH
• Year: 2021
• Print ISBN:
  9781119809913
  9780471187103
• eBook ISBN:
  9781119815143
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Physical & Theoretical Chemistry

This unique book shows how chemistry and physics come together in the solid state and on surfaces. Using a lively, graphic, descriptive approach, it teaches chemists the language that is necessary to understand the electronic structure of extended systems. And, at the same time, it demonstrates how a chemical, frontier-orbital, approach to solid state and surface bonding and reactivity may be constructed.

The book begins with the language of crystal orbitals, band structures and densities of states. The tools for moving back from the highly delocalized orbitals of the solid are then built up in a transparent manner; they include decompositions of the densities of states and crystal orbital overlap populations. Using these tools, the book shapes a meeting ground between detailed quantum mechanical calculations and a chemical frontier orbital perspec- tive. Applications include a general picture of chemisorption, bond-breaking and making in the solid state, bonding in metals, the electronic structure of selected conducting and supercon- ducting structures, dissociation, migration and coupling on surfaces and the forces controlling deformation of extended systems.

INTRODUCTION

Macromolecules extended in one, two, and three dimensions, of biological/natural or synthetic origin, fill the world around us. Metals, alloys, and composites, be they copper or bronze or ceramic, have played a pivotal and a shaping role in our culture. Mineral structures form the base of the paint that colors our walls and the glass through which we look at the outside world. Organic polymers, natural or synthetic, clothe us. New materials—inorganic superconductors, conducting organic polymers—exhibiting unusual electric and magnetic properties, promise to shape the technology of the future. Solid state chemistry is important, alive, and growing.¹

So is surface science. A surface—be it of metal, an ionic or covalent solid, a semiconductor—is a form of matter with its own chemistry. In its structure and reactivity, it will bear resemblance to other forms of matter: bulk, discrete molecules in the gas phase and various aggregated states in solution. And it will have differences. Just as it is important to find the similarities, it is also important to note the differences. The similarities connect the chemistry of surfaces to the rest of chemistry, but the differences make life interesting (and make surfaces economically useful).

Experimental surface science is a meeting ground of chemistry, physics, and engineering.² New spectroscopies have given us a wealth of information, be it sometimes fragmentary, on the ways that atoms and molecules interact with surfaces. The tools may come from physics, but the questions that are asked are very chemical, e.g., what is the structure and reactivity of surfaces by themselves, and of surfaces with molecules on them?

The special economic role of metal and oxide surfaces in heterogeneous catalysis has provided a lot of the driving force behind current surface chemistry and physics. We always knew that the chemistry took place at the surface. But it is only today that we are discovering the basic mechanistic steps in heterogeneous catalysis. It’s an exciting time; how wonderful to learn precisely how Döbereiner’s lamp and the Haber process work!

What is most interesting about many of the new solid state materials are their electrical and magnetic properties. Chemists have to learn to measure these properties, not only to make the new materials and determine their structures. The history of the compounds that are at the center of today’s exciting developments in high-temperature superconductivity makes this point very well. Chemists must be able to reason intelligently about the electronic structure of the compounds they make in order to understand how these properties and structures may be tuned. In a similar way, the study of surfaces must perforce involve a knowledge of the electronic structure of these extended forms of matter. This leads to the problem that learning the language necessary for addressing these problems, the language of solid state physics and band theory, is generally not part of the chemist’s education. It should be, and the primary goal of this book is to teach chemists that language. I will show that it is not only easy, but that in many ways it includes concepts from molecular orbital theory that are very familiar to chemists.

I suspect that physicists don’t think that chemists have much to tell them about bonding in the solid state. I would disagree. Chemists have built up a great deal of understanding, in the intuitive language of simple covalent or ionic bonding, of the structure of solids and surfaces. The chemist’s viewpoint is often local. Chemists are especially good at seeing bonds or clusters, and their literature and memory are particularly well developed, so that one can immediately think of a hundred structures or molecules related to the compound under study. From empirical experience and some simple theory, chemists have gained much intuitive knowledge of the what, how, and why of molecules holding together. To put it as provocatively as I can, our physicis...

Table of contents

• COVER
• TABLE OF CONTENTS
• TITLE PAGE
• COPYRIGHT PAGE
• PREFACE AND ACKNOWLEDGMENTS
• INTRODUCTION
• REFERENCES
• INDEX
• END USER LICENSE AGREEMENT