spin polarized interband and intraband permittivity

[chandan_kumarvishwakarma1]

Dear Users,

I am trying to reproduce optical properties calculations for a half-metallic Heusler compound Co2FeAlSi [ Phys. Rev. B 103, 075146 (2021) ], But I am unable to figure out,

How can I calculate spin polarized interband and intraband permittivity using VASP?

Can we separate out the contribution from majority and minority spins of real and imag part of DF's ?

In this reference, authors have also calculated magneto-optical permittivity and Kerr rotation, can we calculate the same using VASP?

Please help me out regarding the same.

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Warm Regards
Chandan

[alexey.tal]

Hi,

The calculation of the dielectric function for spin-polarized systems can be performed by setting the LOPTICS and ISPIN flags.

If you would like to account for the intraband transitions in the dielectric function, you need to specify the imaginary plasma frequency WPLASMAI.

Unfortunately, it is not currently possible to output the dielectric function for spin channels separately. Such implementations are on the development to-do list, but I can't give you a timeline, so it might be quicker if you implement it yourself.

The Kerr parameters are not calculated by VASP directly, but you can easily obtain them with the eps_xx and eps_xy (see Eq. 6 of Phys. Rev. B 86, 125139 (2012)).

Best,
Alexey

[chandan_kumarvishwakarma1]

Dear Alexey,

Thanks for your reply.
I am still confused about the WPLASMAI tag as there is no detailed documentations are available.
Please let me know, How can I choose the imaginary plasma frequency for different systems?

Regards
Chandan

[alexey.tal]

The imaginary plasma frequency determines the lifetime broadening of the Drude peak, so it should be set to reproduce the experimental spectrum. In your case, if you aim to reproduce the results from Phys. Rev. B 103, 075146 (2021), you can take the same values.