Electrons in Metal: Wave-Particle Duality

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Discussion Overview

The discussion revolves around the behavior of free electrons in a cubic piece of copper, particularly focusing on their wave-particle duality and how they respond to external electric fields. Participants explore theoretical models, the implications of quantum mechanics, and the relationship between electron behavior and classical physics principles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that free electrons in copper can be modeled as existing everywhere as waves, each with a quantum state.
  • Others argue that the wave-function does not collapse to a particle-like behavior unless subjected to a sufficiently energetic external electric field, such as visible light.
  • There is a discussion about the drift velocity of electrons in response to an electric field and how this can be accounted for with electronic wavefunctions.
  • Some participants suggest that electrons can be viewed as wave packets and question the nature of electrons as both particles and waves.
  • One participant emphasizes that the concept of "wave or particle" is misleading, suggesting instead that electrons are quantum objects.
  • There is mention of using the Kubo formulation for a full quantum mechanical description of electron motion, while also questioning the necessity of such complexity when semi-classical models may suffice.

Areas of Agreement / Disagreement

Participants express differing views on the nature of electrons and the adequacy of various models to describe their behavior. There is no consensus on whether electrons should be considered as waves, particles, or a combination of both, nor on the necessity of using complex quantum mechanical models versus simpler semi-classical approaches.

Contextual Notes

Participants note limitations in the models discussed, including the dependence on the definitions of wavefunctions and the conditions under which electrons behave as particles or waves. The discussion also highlights unresolved aspects of how quantum mechanics relates to classical laws of motion.

Karim Habashy
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Hi All,

Lets assume, we have piece of cubic copper of side length 1 cm metal with neutral charge, so:

1) The free electrons in this piece of copper exist everywhere as waves? , each electron with its quantum state.
2) On applying an external electric field the wave-function collapse and they start behaving like particles ?

Are the above conclusions right ?

Thanks
 
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Karim Habashy said:
1) The free electrons in this piece of copper exist everywhere as waves? , each electron with its quantum state.
It is just a model, but that model is not so bad here.
Karim Habashy said:
2) On applying an external electric field the wave-function collapse and they start behaving like particles ?
No. Unless your "electric field" is something like visible light, with sufficient energy to excite electrons.
 
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mfb said:
It is just a model, but that model is not so bad here.
Is there a more accurate model ?
mfb said:
No. Unless your "electric field" is something like visible light, with sufficient energy to excite electrons.
But how can we account for the drift velocity, due to electrons migration by applying an electric field
 
There are electronic wavefunctions for drifting electrons.
 
DrDu said:
There are electronic wavefunctions for drifting electrons.
You mean the electrons behaving as wave packets of plane waves ? , if so, its interesting how a field affects a wave packet.
Can we say an electron is a particle in reaction and a wave in action ?
 
Karim Habashy said:
Is there a more accurate model ?
Depends on what you want to do.
But how can we account for the drift velocity, due to electrons migration by applying an electric field
A wavefunction can have a momentum, corresponding to drifting electrons.

Karim Habashy said:
Can we say an electron is a particle in reaction and a wave in action ?
Forget the whole idea of "wave or particle". An electron is neither. It is a quantum object.
 
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What is your goal? To interpret quantum mechanics? To understand a metal ?
 
my2cts said:
What is your goal? To interpret quantum mechanics? To understand a metal ?
Neither, I am just trying to comprehend, how electrons (quantum particles) exist everywhere in the metal and in the same time obeys Newtons laws of motion under the application of an electric field.
 
You can describe electron motion and charge transport in metals using full quantum mechanical description via the Kubo formulation. But why would you want to if the characteristics that you want to measure can be described sufficiently by the semi-classical Boltzmann transport description? To want to use the full QM picture (which isn't easy at all) to get at those characteristics is like asking a house builder to use Special Relativity to do his job!

Zz.
 
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