I calculated energies per atom of bulk configurations of transition metals in VASP in order to use them as reference energies for adsorption on surfaces, etc. I downloaded POSCAR files from the material project, calculated their energies in VASP, and divided by the number of atoms in the unit cell. I used PAW PBE pseudopotentials. This is what I got.
Then I decided to do similar calculations in DFTK.jl also in PBE. It uses Hartwigsen-Goedeker-Hutter (HGH) pseudopotentials. DFTK.jl gives energies in Hartree, I multiplied them by 27.2114 and got the following picture with completely different numbers:
I understand that different pseudopotentials use different references and cannot be straightforwardly compared. I just did not expect that the numbers would be that different.
Is there a way to take one pseudopotential, make some calculation on it, and compare it with another pseudopotential or to some calculation on that pseudopotential?
I just want know how to check if I have any mistakes in calculations, and to understand what to do and what not to do when using different software for different parts of calculations. For example, I used the same cutoff energies but it probably does not make sense because the cutoff should be different for different pseudopotentials.
Moreover, for certain atoms, DFTK.jl has different versions of a hgh pseudopotential and each gives very different result, so I am confused, which of them to use., e.g. for Ir:
ir-q9: -20.225468 Ha/atom ir-q17: -104.765948 Ha/atom