[Wien] Different Plasma Frequency (PF) for bulk and supercell Na

[Dr. K. C. Bhamu]

Dear sajjad

I am also a beginner but I must suggest you to choose 18*18*3 k points for
1*1*6 supercell in comparison with bulk.
As volume in real space is inversely proportional to volume of reciprocal
space. Larger the volume in real space lower the volume in reciprocal
space. So while computing properties of 1*1*6 structure you are minimizing
your volume in z direction and hence need less k-points.

I appreciate any comment on this from DFT experts.


Sincerely
Bhamu

I have computed PF for bulk Na and its value is  *5.943 eV* with k-mesh
> *18*18*18*.
>
> Then I constructed a supercell 1*1*6
>

...>>>>>>> use 18*18*3 k points for 1*1*6 supercell.

and run the calculation with different k-meshes and obtained PF values. The
> details are
>
> *K-mesh                        PF (x/z components in eV)*
>
> *24*24*24                  5.7097   /   5.8192*
>
>
> *36*36*24                  5.7614   /   5.8098  *
>
>
> *50*50*10                  5.9358   /   5.6280 *
>
> *50*50*30                  5.9365   /   5.8079*
>
> My question is why PF is very sensitive to k-mesh selection? and which
> value of PF is required for correct dielectric constant calculation? Do I
> need *PF = 5.943 eV* for the supercell and then, definitely, need more
> test calculation for right k-mesh selection?
>
> --
> Kind Regards
> Muhammad Sajjad
> Post Doctoral Fellow
> KAUST, KSA.
>
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