Physics 541

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Physics 541
A quantum approach to condensed matter physics
Class 7
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Recapitulation of Class 6
Problem What operator creates plasma
oscillations?
Equation-of-motion approach
Can we find an operator like this for the Coulomb
gas?
So this operator is good if q is big, but not if
it is small.
still no good!
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Recapitulation of Class 6
Remember that plasmon energy squared is linear in
the coupling
becomes
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Recapitulation of Class 6
Can this be related to the concept of a
dielectric constant?
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(No Transcript)
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Look at a sample term in Ueff
Random Phase Approximation
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Add these up to get
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Higher order in V
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ln 2
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Now allow occupation number to be 0, 1, 2, 3,
4,..
Commutator
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For true bosons, N is not conserved
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Convergence of series?