1 - Introduction

Summary

Without physics there is no life

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Summary

Since the discovery of the electron in 1896–1897, the theory of electrons in matter has ranked among the great challenges of theoretical physics. The fundamental basis for understanding materials and phenomena ultimately rests upon understanding electronic structure. This chapter provides a brief outline with original references to early developments of quantum mechanics and the pioneering quantitative theories that foreshadowed most of the methods in use today.

Electrons and nuclei are the fundamental particles that determine the nature of the matter of our everyday world: atoms, molecules, condensed matter, and man-made structures. Not only do electrons form the “quantum glue” that holds together the nuclei in solid, liquid, and molecular states, but also electron excitations determine the vast array of electrical, optical, and magnetic properties of materials. The theory of electrons in matter ranks among the great challenges of theoretical physics: to develop theoretical approaches and computational methods that can accurately treat the interacting system of many electrons and nuclei found in condensed matter and molecules.

Quantum theory and the origins of electronic structure

Although electric phenomena have been known for centuries, the story of electronic structure begins in the 1890s with the discovery of the electron as a particle – a fundamental constituent of matter. Of particular note, Hendrik A. Lorentz modified Maxwell's theory of electromagnetism to interpret the electric and magnetic properties of matter in terms of the motion of charged particles.