<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"> Hi, <br><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><div><p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman"><span style=""> </span>Maybe I have not illustrate problem clearly. </font></span></p>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman">I want to perform EPC calculation on a supercell.</font></span></p>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman"> Take NaCl as a example,</font></span></p><p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><br><span lang="EN-US"></span></p><p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman">The example looks meaningless, NaCl is an insulator. You can try an Al supercell based on primitive unit cell..<br></font></span></p><p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman"><br></font></span></p>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman"> I construct a 2*2*2 supercell in the unit of primitive cell, whose space group is P1</font></span></p>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman"> with the lowest symmetry. We all know that the EPC</font></span></p>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman"> is a much time consuming process. Introducing symmetry </font></span></p>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman">operation to the system can speed the calculation greatly. </font></span></p>
<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman">My question is how can I introduce symmetry to the supercell I mentioned above in the precondition of obtaining physical results.</font></span></p></div>
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<span>If I understood correctly, you would like to know the space group of your 2x2x2 supercell and then use it in EPC calculations. There are several ways to do it. Say, VASP, CRYSTAL03 (but not sure about LMTO47, because it requires only irreducible atomic positions and space group number, too). ISOTROPY code seems to be very useful for this purpose: <a target="_blank" href="http://stokes.byu.edu/isotropy.html">http://stokes.byu.edu/isotropy.html</a></span><br><br>Hope it helps.<br>Bests,<br>Eyvaz.<br><br><div style="border-bottom: 1px solid rgb(153, 153, 153);"></div><br>
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