Dear Gert Van der Zwan,

                                            Thank you for your answer. Actually to calculate the properties of a material in a solvent medium we should calculate the di-electric constant of the solvent. To calculate ground state properties we should mention static di-electric constants and to perform TD-DFT calculations we need both static and dynamic di-electric constant values. From Clausius Mossotti equation we can determine di-electric constant ( I am not sure whether that gives static or dynamic di-electric constant). When we look into Lorentz-Lorenz equation and Clausius Mossotti equation, the only difference we observe is in Clausius Mossotti equation there is epsilon and in Lorentz-Lorenz equation there is a square of refractive index. Equating both the equations we realize that epsilon is equal to square of refractive index. However refractive index is dependent on frequency (From the Lorentz-Lorenz equation). Therefore the epsilon calculated from the Clausius Mossotti equation gives the epsilon value which is frequency dependent which is also called dynamic di-electric constant [Ref 1- Paper attached]. But I found in literature ground state properties are determined making use of dielectric constant calculated from Clausius Mossotti equation [Ref-2-Paper attached]. So I am really confused to sort out the dielectric constant determined using polarizabilities and molar volumes and incorporating in Clausius Mossotti equation give the value of static dielectric constant or dynamic di electric constant?

Mr. Aditya,

Please follow the discussion:

https://www.researchgate.net/post/Do_I_have_to_manually_enter_dielectric_constants_for_PCM_solvents_in_DFT_calculations_in_Gaussian_at_elevated_temperature

 Thank you Prof. Gert Van der Zwan. I am going through the lecture notes you have attached and will get back to you, if i have any doubts in this regard.

Thank you Prof. Ivanova for posting the link.

The density functional method, there  is  method of electron density. At the same time, the dielectric characteristic is dependent on the frequency (dispersion). This means working at different frequencies complexes electrons. This is understandable, but not so easy. Or is not it?

Dielectric tensors are standard property calculations for several DFT codes (Vasp, Octopus, ...), but probably not for Gaussian.

See https://cms.mpi.univie.ac.at/wiki/index.php/Dielectric_properties_of_SiC for example.

Dear Prof Gert Van der Zwan, I was trying to reach you via email, but without luck.

I would be interested to your slides: Theories of dialectrics

Would be possible to share them? I would greatly appreciate. With my regards, Enrico

Gert Van der Zwan