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<p class="MsoNormal"><span style="font-size:11.0pt">Hi folks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I’m trying to setup first an SCF calculation and eventually a band structure and relaxation calculation of a system with a NaCl-like lattice. Right now I have an input file with 64 atoms in a cube shape, which
corresponds to 8 unit cells of the NaCl crystal structure. I’ve specified the CELL_PARAMETERS as well as the atomic coordinates and chosen ibrav = 0. I’m getting the following warning:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Message from routine setup:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> using ibrav=0 with symmetry is DISCOURAGED, use correct ibrav instead<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt">What is the correct solution for setting up my supercell; should I be using ibrav = 1 instead and specifying the vectors for repeating my super cell?<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt">For my own understanding, what is the issue with using symmetry with ibrav=0? By symmetry am I correct to assume that this warning is referring to symmetry
detection within the supercell? If so, how does specifying ibrav=1 help with symmetry detection?<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt">For what it’s worth, it looks like symmetry detection is occurring at some level since the code output “Found identity + ( 0.0000 0.2500 0.2500) symmetry”.
However, I would expect to also see (0.25, 0, 0.25) and (0.25, 0, 0.25) as symmetry operations for an NaCl structure so perhaps there is a problem here after all. Am I understanding correctly?
<o:p></o:p></span></li></ol>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-ligatures:none">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-ligatures:none">Ian Dunn (he/him)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-ligatures:none">ASML Wilton MDEV Analysis Architect</span><span style="font-size:11.0pt;mso-ligatures:none"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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