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Lecture 5: Bloch Theorem
The Bloch theorem is stated and a formal proof is given. The notion of the Brillouin
zone is introduced. It is shown that each zone contains N states, where N is the number of
Bravais lattice unit cells in the sample.
A second p
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Lecture 4: Point Group for Bravais Lattice
The concept of point group is introduced, rst for the Bravais lattice. The classication
of the 14 Bravais lattice is described. The notion of nonsymorphic structure for a general
lattice is introduced, illustra
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Lecture 3: Debye Waller factor and Incommensurate Structures
The Debye Waller factor is derived for the Einstein model. The main point is that lattice
vibrations do not broaden the Bragg peaks, only reduce their magnitude. Examples of
incommensurate lat
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Lecture 2: Crystalline Lattice
The Bravais lattice is dened and several examples given. The basis vector is introduced
for a general lattice. The theory of diraction is derived, showing that Bragg refraction
occurs when the momentum transfer equals a re
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Lecture 1: Free Electron Model
Sommerfelds free fermion model for metals. Specic heat is linear in T and spin suscep
tibility is T independent. Conductivity is described by the Drude model. The dimensionless
number rs is introduced as the ratio between