<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;"><DIV>Dear Wien2k users,<BR> 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<BR>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<BR>Fermi levels (known as Fermi level pinning). The length after which this interfacial effect or perturbation gets screened out is known as “Screening Length”.<BR>It is reported that (I will provide references if needed) this length in metals is usually shorter than ONE Angstrom. <BR> 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<BR>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<BR>magnetization has not yet become screened. From this two conclusions can be made:<BR> (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. <BR> (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.</DIV>
<DIV> </DIV>
<DIV> 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<BR>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?</DIV>
<DIV><BR>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.</DIV>
<DIV>Sorry that my question became so lengthy. Any help would be greatly appreciated.</DIV>
<DIV> </DIV>
<DIV>Thank you,<BR>Bahram Abedi</DIV></td></tr></table><br>
<hr size=1> <a href="http://sg.rd.yahoo.com/aa/mail/domainchoice/mail/signature/*http://mail.promotions.yahoo.com/newdomains/aa/"> New Email addresses available on Yahoo! </a> <br>
Get the Email name you've always wanted on the new @ymail and @rocketmail.<br>
Hurry before someone else does!