I found in an article [1] the following definition of FNV (Freysoldt, Neugebauer and Van de Walle) energy correction term for a charged defect in a cubic supercell:

$$E_{\text{corr}}=\frac{\alpha_Mq^2}{2\epsilon L}-q\Delta V^{\text{DFT/pc}}_{q/0}\tag{1}$$

Then it says:

$\varepsilon$ is the macroscopic dielectric constant of the medium. For systems which do not undergo significant relaxation, the use of the high-frequency dielectric constant $\varepsilon_\infty$ is appropriate to describe the screening. Otherwise, one needs to use the static dielectric constant $\varepsilon_0$.

What is the physical difference between $\varepsilon_\infty$ and $\varepsilon_0$? Is $\varepsilon_\infty$ the real part of the dielectric constant at infinite wavelength from an optical calculation to get $\mathcal{Re}(\varepsilon)$ and $\mathcal{Im}(\varepsilon)$? Would $\varepsilon_0$ be what can be accessed experimentally forming a capacitor?

  1. Wei Chen and Alfredo Pasquarello 2015 J. Phys.: Condens. Matter 27 133202 DOI: 10.1088/0953-8984/27/13/133202
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    $\begingroup$ Welcome to the site! I added some additional formatting to your post. If I made any errors in transcribing the equation, you can edit them to how you want using Mathjax syntax. $\endgroup$
    – Tyberius
    Aug 9, 2021 at 19:52
  • $\begingroup$ +1 and welcome to our new community! Thank you so much for contributing your question here and we hope to see much more of you in the future !!! I've commented our your second question because we have a policy of only one question/post. This will hopefully make it easier for our community to help you with the question! $\endgroup$ Aug 21, 2021 at 18:10
  • $\begingroup$ Related questions on researchgate and matsci forum $\endgroup$
    – Tyberius
    Nov 10, 2021 at 19:32
  • $\begingroup$ Rogerio, were those links from Tyberius helpful? Has there been any luck/update on this question? $\endgroup$ Dec 25, 2021 at 21:30
  • $\begingroup$ This question appears to be abandoned. It can be reopened if OP addresses suggestions in the comments or anyone would like to add an answer. $\endgroup$
    – Tyberius
    Jan 2, 2022 at 20:29