Why do we use Local field correction?

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Discussion Overview

The discussion centers on the concept of local field correction in the context of dielectric materials. Participants explore the implications of the dielectric constant as a macroscopic quantity and the necessity of local field corrections to account for variations at the atomic level.

Discussion Character

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

Main Points Raised

  • Some participants note that the dielectric constant is a macroscopic quantity derived from averaging effects across many atoms or molecules.
  • Others argue that there can be significant deviations from this average, with electric fields near atoms potentially becoming very large and even changing sign.
  • It is proposed that local field corrections can be incorporated by using a dielectric function that accounts for spatial dispersion, suggesting that the dielectric constant may not be sufficient on its own.
  • A participant questions whether local field corrections can be included in the dielectric constant itself, leading to a clarification that the effects cannot be captured by a single number.

Areas of Agreement / Disagreement

Participants express differing views on the adequacy of the dielectric constant alone to describe electric fields in materials, indicating that multiple competing perspectives remain on the necessity and implementation of local field corrections.

Contextual Notes

Limitations include the dependence on definitions of dielectric constant versus dielectric function, as well as the unresolved nature of how local field corrections can be effectively represented in theoretical models.

hokhani
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Knowing the dielectric constant of a medium we can earn the electric field at any point in that medium which is deferent from the applied external electric field. So why do we use the Local field correction?
 
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The dielectric constant is a macroscopic quantity - you get this value if you average the effects of many atoms/molecules. If you look closer, you might find small deviations from that average.
 
There are huge differences from the average.
E gets huge and changes sign near atoms.
 
You can include local field corrections by working with a dielectric function which includes spatial dispersion. In the case of a homogeneous medium, this means that epsilon is a tensor which depends on frequency omega and wavevector k.
 
DrDu said:
You can include local field corrections by working with a dielectric function which includes spatial dispersion. In the case of a homogeneous medium, this means that epsilon is a tensor which depends on frequency omega and wavevector k.[/QUOTE

By this, do you mean that we can also include local field correction in the dielectric constant?
 
hokhani said:
[
By this, do you mean that we can also include local field correction in the dielectric constant?

I wrote dielectric function instead of dielectric constant as the effects cannot be included in a single number.
 

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