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Explore the principles of Quantum Mechanics - Hund’s rules, spectroscopic symbols, and solid state models - to understand the behavior of electrons in a structured manner. Familiarize yourself with principles like the free electron gas theory and Bloch’s theorem for modeling solids. Dive into topics like electron wave functions, Fermi surfaces, and band structures in the context of condensed matter physics.
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Physics 451 Quantum mechanics I Fall 2012 Dec 3, 2012 Karine Chesnel
Homework Quantum mechanics • Last two assignment • HW 23 Tuesday Dec 4 • 5.9, 5.12, 5.13, 5.14 • HW 24 Thursday Dec 6 • 5.15, 5.16, 5.18, 5.19. 5.21 Wednesday Dec 5Last class / review
Periodic table Quantum mechanics Hund’s rules • First rule: seek the state with highest possible spin S • (lowest energy) • Second rule: for given spin S, the state with highest possible • angular momentum L has lowest energy • Third rule: • If shell no more than half filled, the state with J=L-S • has lowest energy • If shell more than half filled, the state with J=L+S • has lowest energy
Quiz 32a Quantum mechanics What is the spectroscopic symbol for Silicon? Si: (Ne)(3s)2(3p)2 A. B. C. D. E.
Quiz 32b Quantum mechanics What is the spectroscopic symbol for Chlorine? Cl: (Ne)(3s)2(3p)5 A. B. C. D. E.
Solids Quantum mechanics e- What is the wave function of a valenceelectron in the solid?
Solids Quantum mechanics e- Basic Models: • Free electron gas theory • Crystal Bloch’s theory
Free electron gas Quantum mechanics e- e- lz ly lx Volume Number of electrons:
Free electron gas e- 3D infinite square well 0 inside the cube outside Quantum mechanics
Free electron gas e- Separation of variables Quantum mechanics
Free electron gas Bravais k-space Quantum mechanics
Free electron gas Fermi surface Free electron density Quantum mechanics Bravais k-space
Free electron gas Fermi surface Total energy contained inside the Fermi surface Quantum mechanics Bravais k-space
Free electron gas Fermi surface Quantum mechanics Solid Quantum pressure Bravais k-space
Solids e- Fermi surface Bravais k-space Number of unit cells Quantum mechanics
Solids e- Pb 5.15: Relation between Etot and EF Pb 5.16: Case of Cu: calculate EF , vF, TF, and PF Fermi surface Bravais k-space Quantum mechanics
Solids e- Fermi surface Bravais k-space Number of unit cells Quantum mechanics
Solids Bloch’s theorem Quantum mechanics Dirac comb V(x)
Solids Quantum mechanics Circular periodic condition V(x) x-axis “wrapped around”
Solids Quantum mechanics Solving Schrödinger equation V(x) a 0
Solids Quantum mechanics Boundary conditions V(x) a 0
Solids • Discontinuity of Quantum mechanics Boundary conditions at x = 0 V(x) a 0 • Continuity of Y
Solids Band structure Quantum mechanics Quantization of k: Pb 5.18 Pb 5.19 Pb 5.21
Quiz 33 Quantum mechanics In the 1D Dirac comb model how many electrons can be contained in each band? A. 1 B. 2 C. q D. Nq E. 2N
Solids Insulator: band entirely filled ( even integer) 2N electrons (2e in each state) Quantum mechanics Quantization of k: Band structure E Conductor: band partially filled N states Band Gap Semi-conductor: doped insulator N states Band Gap N states Band