Polarizability and permittivity

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    Permittivity
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Discussion Overview

The discussion focuses on methods to calculate the polarizability and permittivity of arbitrary compounds, specifically mentioning oxygen as an example. The scope includes theoretical approaches and computational methods relevant to these properties.

Discussion Character

  • Technical explanation, Exploratory

Main Points Raised

  • One participant seeks effective methods for calculating polarizability and permittivity of compounds.
  • Another participant inquires whether the focus is on static or frequency-dependent properties.
  • The original poster expresses a preference for frequency-dependent calculations but acknowledges that static calculations would suffice in many cases.
  • A later reply suggests using a finite field approach to calculate static polarizability, invoking the Hellman-Feynman theorem and noting the need for diffuse basis sets for accuracy.
  • This reply also mentions that calculating permittivity may require specialized software, referencing the CFOUR package for coupled cluster methods and suggesting that density functional methods might have other options.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific method for permittivity calculations, and there are differing views on the preferred approach for polarizability calculations.

Contextual Notes

The discussion highlights the need for specific computational resources and methods, as well as the importance of basis set selection for accurate results. There are unresolved aspects regarding the software options for permittivity calculations.

Gavroy
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hi

i am looking for a method to calculate the polarizability and permittivity of arbitrary compounds like e.g. oxygen. does anybody know an effective method for at least one of the two constants?
 
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static or frequency dependent?
 
well, i would prefer the last one, but static would do the job in most cases too...
 
in that case you can calculate the static polarizability with a finite field approach using many electronic structure programs. By this you invoke the Hellman-Feynman theorem and calculate the polarizability as numerical second derivative with respect to a finite electric field. Beware that you need very diffuse basis sets in order to calculate accurate polarizabilities. (doubly augmented Dunning-type sets or Sadlej-type sets). This approach is generally very accurate if high-level electronic structure methods can be employed (say, CCSD(T))

Permittivity is a different topic. This may require special software to get it right. The CFOUR-package probably has something to do it at coupled cluster level, but it might need some getting used to. At density functional level there may also be other packages, but I don't know about them.
 

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