Are permittivity and permeability quantities that can be predicted?

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Discussion Overview

The discussion revolves around the predictability of permittivity and permeability of substances based on their atomic composition. Participants explore whether these quantities can be calculated from first principles and the complexities involved in such predictions, including the role of material processes.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Some participants propose that it is possible to calculate the permittivity of a substance ab initio, although they note that the theory involved is not elementary.
  • It is suggested that the dielectric function, which depends on frequency and wavenumber, also determines permeability.
  • Others argue that permeability is more complex and is influenced by factors such as domain size and crystal size, which are not solely determined by atomic composition but also by material processing.
  • A specific example is provided where adding silicon increases permeability, despite silicon not being ferromagnetic.

Areas of Agreement / Disagreement

Participants express differing views on the predictability of permeability, with some asserting it can be calculated while others emphasize its complexity and dependence on additional factors. The discussion remains unresolved regarding the extent to which these properties can be predicted from atomic composition alone.

Contextual Notes

Limitations include the complexity of the theories involved and the dependence on material processing, which may not be fully addressed in the discussion.

DuckAmuck
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TL;DR
Can these be derived from other chemical properties?
For example, can you predict the permittivity and permeability of a substance if you know what the atomic composition is? Is it a stat mech problem?
 
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DrDu said:
Yes, it is possible to calculate the permittivity of a substance ab initio.
The theory is not elementary:
http://susi.theochem.tuwien.ac.at/events/ws2015/rolask_optic.pdf
In principle, the dielectric function in dependence of frequency and wavenumber also determines the permeability.
Amazing. Thank you.
 
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Permeability, however, is more of a dark art. It's related to domain size, which is related to crystal size, which isn't just a matter of composition, it's a matter of process. For example, adding silicon usually increases permeability but it isn't even ferromagnetic.
 
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