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Dear VASP officer


Hello, I'm a VASP beginner and when I see the download list of POTCAR(pseudopotential), there are no K POTCAR file but only K_pv, K_sv, K_sv_GW.

Could you tell me why there are no K_normal POTCAR file? Also how can I get this K_normal POTCAR file? (There are Li_normal and Na_normal file in the list but only K is not exist.)

Thank you for reading.

Hello!

Welcome to the VASP forum! Can you please tell me to which download list you are referring to? As far as I know none of the POTCAR files which can be downloaded from the VASP portal comes with the suffix _normal. Instead, the "standard" version will have no suffix at all. My guess is that these were made available to you with the additional label _normal. If so, I can confirm that there is indeed no "standard" POTCAR for K. However, often the "standard" version may not automatically be the recommended one. Our list of recommended POTCAR files with additional explanations can be found here:

Available_PAW_potentials

As you can see for DFT calculations there is no K POTCAR but only K_pv and K_sv, where the latter one is recommended. Also note that Li_sv and Na_pv are actually recommended for Li and Na, respectively.

So why is there no "standard" K POTCAR? If you have a look at the electronic configuration, you will find that K is written as [Ar]4s1. Hence, the "standard" version would only include the 4s1 as a single valence electron. Because this will usually not suffice to give reasonable material properties, only the _pv and _sv versions are provided, where 3p and (3s + 3p) electrons are also treated as valence electrons, respectively. For K the recommended K_sv then has nine valence electrons, i.e., 3s2 + 3p6 + 4s1. Actually the same argument holds for the other elements in the first two columns of the periodic table (sometimes even extending to the following columns, e.g., Y, Zr, Nb), so you will not find the "standard" POTCAR files for these elements.

All the best,

Andreas Singraber

Dear Andreas Singraber

Thank you very much sir Andreas Singraber, my curiosity was totally solved.
Also thanks for letting me know about avilable PAW potentials.
I didn't have a basic knowledge of INCAR design, but I think I can lay the basis through this.
Thank you again for your kind reply.

Sincerely, Woojin Jeon