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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">With my interpretation problem being solved (see previous summarizing mail), I’m left with the two questions about the value and “phase” of the zigzag potentials. For clarity, I repeat here these two questions (copied
from the initial post).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Stefaan<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">================<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I know that the Berry phase approach is the recommended way nowadays for applying an external electric field in wien2k. However, for a quick test I resorted to the old zigzag potential that is described in the usersguide,
sec. 7.1.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">It works, but I have some questions to convince me that I’m interpreting it the right way.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The test situation I try to reproduce is from this paper (<a href="https://doi.org/10.1103/PhysRevLett.101.137201">https://doi.org/10.1103/PhysRevLett.101.137201</a>), in particular this picture (<a href="https://journals.aps.org/prl/article/10.1103/PhysRevLett.101.137201/figures/1/medium">https://journals.aps.org/prl/article/10.1103/PhysRevLett.101.137201/figures/1/medium</a>
). It’s a free-standing slab of bcc-Fe layers, with an electric field perpendicular to the slab. For convenience, I use only 7 Fe-monolayers (case.struct is pasted underneath). Spin orbit coupling is used, and the Fe spin moments point in the positive z-direction.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">This is the input I used in case.in0 (the last line triggers the electric field) :<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">TOT XC_PBE (XC_LDA,XC_PBESOL,XC_WC,XC_MBJ,XC_REVTPSS)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">NR2V IFFT (R2V)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> 30 30 360 2.00 1 min IFFT-parameters, enhancement factor, iprint<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">30 1.266176 1.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Question 1: The usersguide tells “The electric field (in Ry/bohr) corresponds to EFIELD/c, where c is your c lattice parameter.” In my example, EFIELD=1.266176 and c=65.082193 b, hence the electric field should be 0.019455
Ry/bohr. That’s 0.5 V/Angstrom. However, by comparing the dependence of the moment on the field with the paper cited above, it looks like that value for field is just half of what it should be (=the moment changed as if it were subject to a field of 1.0 V/Angstrom).
When looking at the definition of the atomic unit of electric field (<a href="https://physics.nist.gov/cgi-bin/cuu/Value?auefld">https://physics.nist.gov/cgi-bin/cuu/Value?auefld</a>), I see it is defined with Hartree, not Rydberg. This factor 2 would explain
it. Does someone know whether 2*EFIELD/c is the proper way to get the value of the applied electric field in WIEN2k?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Question 2: It is not clear from the userguide where the extrema in the zigzagpotential are. Are they at z=0 and z=0.5, as in fig. 6 of
<a href="http://dx.doi.org/10.1103/PhysRevB.63.165205">http://dx.doi.org/10.1103/PhysRevB.63.165205</a> ? I assumed so, that’s why the slab in my case struct is positioned around z=0.25. Adding this information to the usersguide or to the documentation in the
code would be useful. (or alternatively, printing the zigzag potential as function of z by default would help too)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">blebleble s-o calc. M|| 0.00 0.00 1.00<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FR-BE" style="color:black;mso-fareast-language:NL-BE">P 7 99 P<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FR-BE" style="color:black;mso-fareast-language:NL-BE"> RELA<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FR-BE" style="color:black;mso-fareast-language:NL-BE"> 5.423516 5.423516 65.082193 90.000000 90.000000 90.000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FR-BE" style="color:black;mso-fareast-language:NL-BE">ATOM -1: X=0.00000000 Y=0.00000000 Z=0.12500000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FR-BE" style="color:black;mso-fareast-language:NL-BE">
</span><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">MULT= 1 ISPLIT=-2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">Fe1 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 1.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 0.0000000 1.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">ATOM -2: X=0.00000000 Y=0.00000000 Z=0.37500000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> MULT= 1 ISPLIT=-2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">Fe2 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 1.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 0.0000000 1.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">ATOM -3: X=0.00000000 Y=0.00000000 Z=0.20833333<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> MULT= 1 ISPLIT=-2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">Fe3 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 1.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 0.0000000 1.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">ATOM -4: X=0.00000000 Y=0.00000000 Z=0.29166667<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> MULT= 1 ISPLIT=-2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">Fe4 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 1.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 0.0000000 1.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">ATOM -5: X=0.50000000 Y=0.50000000 Z=0.16666667<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> MULT= 1 ISPLIT=-2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">Fe5 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 1.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 0.0000000 1.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">ATOM -6: X=0.50000000 Y=0.50000000 Z=0.33333333<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> MULT= 1 ISPLIT=-2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">Fe6 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 1.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 0.0000000 1.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">ATOM -7: X=0.50000000 Y=0.50000000 Z=0.25000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> MULT= 1 ISPLIT=-2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">Fe7 NPT= 781 R0=.000050000 RMT= 2.22000 Z: 26.00000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE">LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 1.0000000 0.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 0.0000000 0.0000000 1.0000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:black;mso-fareast-language:NL-BE"> 8 NUMBER OF SYMMETRY OPERATIONS<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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