<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman">Dear WIEN2k users</font></p>
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<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman">In the ORB section of user's guide, the below statements were written:</font></p>
<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman">If LDA+U is used in an unrestricted, general way, it introduces an orbital field in the calculation. If the LDA+U orbital polarization is not needed, it is sufficient to run real version of LAPW1, which then automatically puts the orbital field equal to zero. For systems without the center of inversion when LAPW1 must be complex, an extra averaging of LDA+U potential is necessary.
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<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman">I have some questions.</font></p>
<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman">1. Is this statement true? When we have a system with the centre of inversion, all of the component of orbital dependent potential will be real.
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<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman">2. Dose the real version of LAPW1 put the orbital field equal to zero in a system with the centre of inversion that has only real component of orbital dependent potential?
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<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman">3. How can we do the extra averaging of the LDA+U potential for system without the centre of inversion, when LAPW1 must be complex?</font></p>
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<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman">Best regards</font></p>
<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt"><font face="Times New Roman">Vahid Ghanbarian.</font></p>