# Tag Info

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In principle yes, but the electrons will respond at around their natural frequency of oscillation. This is the plasma frequency and for most metals is around the frequency of visible light or about $10^{14}$ Hz. So the electrons will only be displaced for a few fractions of a picosecond. The analogy with sound is that the motion creates a sound wave that ...

3

An atom in isolation offers a potential well, and electrons form bound states in the well. The energy of those bound states can be calculated exactly in the case of a single-electron (hydrogen-like) atoms or by variational computational methods for more complicated cases. Now when you put several atoms together in a tight and regular array, they offer a ...

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The normal ordening is a way to say: ''we throw away the zero-point energy'' (since it becomes infinity and wa say we only look at energy-differences), or to put it in the words of A. Zee: ''Create before you annihalite''. The chronological ordening comes in when you calculate the Feynman propagator (also called the Green's function), which is basically the ...

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$k$ is just a quantum number. $\hbar k$ gets its name "crystal impulse" from the fact, that the formula for a band structure without interaction (free electrons) coincides with the formula you get with the definition of classical impulse in terms of $k$, but it is NOT an actual impulse. For a free electron we have the energy dispersion:  \epsilon(k) = ...

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The dispersion relation gives you information regarding the relation between momentum of electrons, and energy of such electron. Heisenberg's uncertainty principle relates uncertainty in the position versus uncertainty in momentum, which is a very different issue. If you consider a single massive free particle, it also possesses a dispersion relation in the ...

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In a single free atom, electrons have well defined energy levels and are somewhat bound to atom. Consider the following quantum mechanical model of atom to get an idea about an isolated atom. When all this isolated atoms come together to form the crystal, the atoms do not have well defined energy levels. There will be molecular orbitals. When the atoms ...

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The intuition is that the valence electrons are so far away from their nucleus that when they combine to form metals, they feel the attraction of all the other nuclei as strongly as from theirs. In a more rigorous description, the orbitals for the valence electrons fully overlap with their neighbouring atoms, so their "play field" extends all over the ...

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Strictly speaking (a) is correct. But in cold temperature under the freezing point, the motion would be called "tiny vibration", and molecules cannot move freely as in liquid or gas state. If the "move" in (b) means free motion including replacement with neighboring molecules, (b) may be correct also. But the "move" includes tiny vibration, (b) is wrong. ...

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The electron motion does feed back to the oscillator, but that is another diagram, known as the bubble diagram, in which you calculate the self-energy correction of the oscillator. That self-energy presumably contains imaginary part, which is then interpreted as the damping of the oscillator. You can either calculate the self-energy corrections ...

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I am assuming that those are bare Green's function in the diagram, and the dotted line is the harmonic oscillator $<a^\dagger a>$ ? 1) The diagram you drew does not "know" about the damping of the harmonic oscillator, (although it is closely related by the optical theorem and such to the diagrams that would calculate the damping, I suppose that is ...

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Perhaps this wiki link of Epitaxial growth would be helpful. My answer might be technically wrong what i am gonna write down is what i remember about. While adding the impurity in the fabrication of semiconductor devices we break up the whole crystalline structure and after adding the impurity the atoms rearrange them to form a regular crystal while getting ...

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