[Wien] Help about calculating Electron Density

[Bahram Abedi]

Dear Wien2k users,
       I have a question about calculating the electronic charge density but prior to my question please let me give a brief introduction to the problem. We know
that when two materials of different type come into contact with each other, depending on their work function a charge transfer will occur at the interface to align the
Fermi levels (known as Fermi level pinning). The length after which this interfacial effect or perturbation gets screened out is known as “Screening Length”.
It is reported that (I will provide references if needed) this length in metals is usually shorter than ONE Angstrom. 
        I have built a supercell consisting of 3 monolayers of MgO sandwiched at each side by 4 monolayers of Fe. After the scf is converged I read the magnetic moment corresponding
to the Fe spheres counting from the interface equal to 2.85, 2.49, 2.44, and 2.42 magneton bohrs, respectively. This means that after 4 monolayers the interface induced
magnetization has not yet become screened. From this two conclusions can be made:
          (i) The electronic charge arrangement up to fourth atomic layer is different from that of  bulk Fe and then the screening length must be at least 2*a where “a” is the lattice constant of Fe.  
          (ii) After a fraction of an angstrom the electronic charge gets its bulk distribution and the magnetization that we read at the fourth layer is a result of a perturbed spin configuration.
 
       I think the screening length can be read visually from a proper calculation of the corresponding Electron Density plotted across the interface. However, I tried to
calculate this property using different options (especially, RHO & ADD in line 6 of case.in5) and choosing Emin and Emax slightly below and above the Fermi energy, respectively.The problem is that I cannot see any difference in the Density Plots in going away from the interface. May you please tell me if my switch options (RHO & ADD) are correct?

Of course, the total or spin-dependent charge corresponding to each layer can also be read from the “scf” file, but this is just the charge inside each sphere and is not including the layer-dependent interstitial charge.
Sorry that my question became so lengthy. Any help would be greatly appreciated.
 
Thank you,
Bahram Abedi


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