Dear Puspa,

The macroscopic dielectric constant of a material is the volume-averaged response to an applied external force field (electromagnetic field). This macroscopic quantity can be evaluated according to Maxwell’ equations (ϵ = 1+ P/ ζ), where P is the polarization density and ζ is applied field.

On the other hand, the frequency and wave-vector k-dependent dielectric response ϵ(q, ω) of a system can be calculated from the ground state band structure by ab-initio or approximate methods (DFT, DFpT, GWA,...). The resulting microscopic dielectric function is not generally the same as the measured (macroscopic) dielectric function, because of many reasons.

The macroscopic dielectric function can be defined as : ϵ∞ = ϵ(q, ω-->∞ ). Therefore, ignoring the local field (the off-diagonal element of dielectric matrix).

Thank you, Dr. Muhammad El-Saba for your reply and suggestions.

The various method explaining dielectric properties are quite interesting. Here I want a better understanding on the contribution of ionic and electronic part?

Hello,

CINEMAS is a GUI based simulation platform.

'Dielectric module' within CINEMAS, calculates dielectric constants, and piezoelectric tensor, automatically through easy GUI.

One can start only with the structure file, and remaining calculation is prepared, performed, and post-processed automatically using VASP.

Find a video tutorial here: https://youtu.be/-haMxXPBIFw

Other CINEMAS tutorials https://www.youtube.com/channel/UCi3u3VAMUqfcdyNDQbSzSHw

Regards

Kapil Gupta

Many thanks Dr. Muhammad Hamza El-Saba and Dr. Kapil Gupta.

I have read and Applied CINEMAS but could not succeed. Kapil Gupta Muhammad Hamza El-Saba Samir Paudel