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<font face="Dialog" size="2">Dear WIEN2k users,</font> </p>
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<font face="Dialog" size="2">I have a question concerning the calculation of the dielectric tensor.</font> </p>
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<font face="Dialog" size="2">I used the standard procedure to obtain the components of the dielectric tensor for an optically anisotropic slab (converged density -> optic -> joint -> kram). However, in the kram output file "case.epsilonup" I obtain negative values (see below) for some of the tensor components at some energies. I found that the user guide states on page 151: "Warning: Negative values for epsilon_2 may occur due to negative weights in Blöchl's tetrahedron method". What does this actually mean? Are these values useless/unphysical then?</font> </p>
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<font face="Dialog" size="2">As I would like to postprocess the data for the dielectric tensor I need to know how to deal with these negative values. Is it sufficient just to take the absolute value? If not, how can I interpret these negative values for some tensor components?</font> </p>
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<font face="Dialog" size="2">Below you see a part of the "case.epsilonup" file showing the negative values:</font> </p>
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<font face="Dialog" size="2">===== case.epsilonup ==========================================================================</font> </p>
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<font face="Dialog" size="2"># </font> </p>
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<font face="Dialog" size="2"># Lorentzian broadening with gamma= 0.100000 [eV]</font> </p>
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<font face="Dialog" size="2"># Im(epsilon) shifted by 0.0000 [eV]</font> </p>
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<font face="Dialog" size="2"># No intraband contributions added</font> </p>
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<font face="Dialog" size="2">#</font> </p>
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<font face="Dialog" size="2"># Energy [eV] Re_eps_xx Im_eps_xx Re_eps_yy Im_eps_yy Re_eps_xy Im_eps_xy</font> </p>
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<font face="Dialog" size="2">#</font> </p>
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<font face="Dialog" size="2"> 0.013610 0.355073E+03 0.267270E+03 0.379411E+03 0.284541E+03 -0.433910E+01 -0.111993E+01</font> </p>
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<font face="Dialog" size="2"> 0.040820 0.320451E+03 0.295130E+03 0.341538E+03 0.316236E+03 -0.432648E+01 -0.321273E+01</font> </p>
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<font face="Dialog" size="2"> 0.068030 0.268282E+03 0.302792E+03 0.284004E+03 0.326426E+03 -0.343964E+01 -0.472158E+01</font> </p>
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<font face="Dialog" size="2"> 0.095240 0.216111E+03 0.294926E+03 0.225588E+03 0.319308E+03 -0.210235E+01 -0.530955E+01</font> </p>
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<font face="Dialog" size="2"> 0.122450 0.171960E+03 0.280008E+03 0.175154E+03 0.303207E+03 -0.899641E+00 -0.512592E+01</font> </p>
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<font face="Dialog" size="2"> 0.149660 0.135931E+03 0.264191E+03 0.133648E+03 0.284249E+03 -0.871710E-01 -0.458024E+01</font> </p>
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<font face="Dialog" size="2"> 0.176870 0.105154E+03 0.249611E+03 0.991686E+02 0.264968E+03 0.386425E+00 -0.398342E+01</font> </p>
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<font face="Dialog" size="2"> 0.204090 0.772605E+02 0.235509E+03 0.700520E+02 0.245693E+03 0.658656E+00 -0.345529E+01</font> </p>
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<font face="Dialog" size="2"> 0.231300 0.517615E+02 0.220269E+03 0.455810E+02 0.226285E+03 0.825314E+00 -0.300510E+01</font> </p>
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<font face="Dialog" size="2"> 0.258510 0.295843E+02 0.203095E+03 0.254419E+02 0.206806E+03 0.930218E+00 -0.261269E+01</font> </p>
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<font face="Dialog" size="2"> 0.285720 0.117812E+02 0.184586E+03 0.942771E+01 0.187538E+03 0.985082E+00 -0.226081E+01</font> </p>
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<font face="Dialog" size="2"> 0.312930 -0.144786E+01 0.166031E+03 -0.269328E+01 0.168949E+03 0.988609E+00 -0.195118E+01</font> </p>
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<font face="Dialog" size="2"> 0.340140 -0.107062E+02 0.148526E+03 -0.113783E+02 0.151602E+03 0.953669E+00 -0.169726E+01</font> </p>
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<font face="Dialog" size="2"> 0.367350 -0.168993E+02 0.132631E+03 -0.173011E+02 0.135876E+03 0.903225E+00 -0.149950E+01</font> </p>
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<font face="Dialog" size="2"> 0.394570 -0.208346E+02 0.118478E+03 -0.211441E+02 0.121895E+03 0.853612E+00 -0.134912E+01</font> </p>
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<font face="Dialog" size="2"> 0.421780 -0.231246E+02 0.106034E+03 -0.234971E+02 0.109621E+03 0.817793E+00 -0.123489E+01</font> </p>
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<font face="Dialog" size="2">===============================================================================================</font> </p>
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<font face="Dialog" size="2">Any help would be greatly appreciated.</font> </p>
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<font face="Dialog" size="2">Best regards,</font> </p>
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<font face="Dialog" size="2">Sebastian Putz</font>
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<font face="Dialog" STYLE="font-size: 10pt"><br>================================<BR>Dipl.-Phys. Sebastian Putz<BR>Institute of Theoretical Physics (Group Prof. Fabian)<BR>University of Regensburg<BR>Universitätsstraße 31<BR>93040 Regensburg, Germany<BR>Tel.: 0941 943 2032<BR>E-mail: sebastian.putz@physik.uni-regensburg.de<BR><br><br></font></body>
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