Electronic Structur

Electronic Structur

In Chapter 9 on electronic structure we consider another aspect ofthe structure ofmate- 

rials, namely the electronic structure. The basic ideas relating to electronic structure

include a consideration of the arrangement of atoms and molecules as was introduced 

in Chapters 2 and 3 plus the addition of a consideration of the interactions of the atoms 

or molecules in their various structural motifs. The interactions among atoms and 

molecules is handled using quantum mechanics. Quantum mechanics enables chemists 

to estimate, if not calculate, the structure of many important molecules using the 

Schrödinger equation. Similarly quantum mechanics enables the calculation of the 

allowed and disallowed energies for the electrons in an array of atoms or molecules in 

condensed phases,such as liquids or solids.The allowed energies are called energy bands, 

and the disallowed energies are called the forbidden energy gaps (FEG) or simply band 

gaps.An old (1931) but useful model for the calculation of electronic energy band struc- 

ture for solids is presented,the Kronig-Penney (KP) model.Despite its simplicity the KP 

model contains many of the important physical ideas that are used in more modern 

models, but without difficult mathematics. Consequently the KP model is useful as a 

vehicle to understand the origin ofallowed electronic energy bands and gaps,but the KP 

model does not enable quantitative estimations of energy bands. Nonetheless, many 

important conclusions can be made regarding the electronic structure of materials using 

the KP model. Associated with the energy band structure is an extensive nomenclature 

and representation language,and this language is introduced to describe electron energy 

band structure. In this chapter there is heavy reliance on the structural ideas and recip- 

rocal space that were introduced in Chapters 2 and 3. 

It is clear that fundamental to understanding electronic and optical properties of 

solids and the devices is the electronic energy band structure; thus Chapters 10 and 11 

make heavy use of the ideas developed in this chapter.Furthermore modern ideas about 

nanotechnology that include quantum well structures, quantum dots, and other small 

intricate structures are understood in terms of the energy band structure and the com- 

parisons that are made to larger devices.

Ramon A. Carmona C

C.I 17646653

CRF

http://media.wiley.com/product_data/excerpt/71/04716959/0471695971.pdf

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