Why do we use Local field correction?

AI Thread Summary
The dielectric constant of a medium is a macroscopic property that averages the effects of many atoms or molecules, but local field corrections are necessary to account for deviations at the atomic level. These corrections reveal significant variations in the electric field near atoms, where the field can become very large and even change direction. To incorporate local field effects, a dielectric function that includes spatial dispersion is used, which treats the dielectric constant as a tensor dependent on frequency and wavevector. This approach acknowledges that a single value for the dielectric constant is insufficient to capture the complexities of the medium. Understanding these nuances is crucial for accurately describing the behavior of electric fields in various materials.
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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