<div dir="ltr"><div><div><div><div><br></div>Dear Farshad,<br><br></div>The fractional occupancy could usually be treated either by making a supercell which is a bit expensive as usually a big cell would be required or by a method called virtual crystal approximation (VCA) that work well mostly for the neighboring atoms but it might works in your case as Ni and Fe are not far a way from each other in the periodic table of element, just google virtual crystal approximation ! you will find more details.<br><br></div>Cheers,<br></div>Salman<br><div><div><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Feb 8, 2016 at 2:32 PM, Farshad Nejadsattari <span dir="ltr"><<a href="mailto:fneja083@uottawa.ca" target="_blank">fneja083@uottawa.ca</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><span style="font-size:12.8px"><span style="font-size:12.8px">Dear Professor Blaha, Wien2k community and experts,</span><div style="font-size:12.8px"><br></div></span><div style="font-size:12.8px"> I am working on the compound Al72Ni9Fe19. This system crystallizes in the space group P63/mmc (No. 194). Two of the Wyckoff sites are partially occupied by Fe and Ni atoms, I would like to know how to construct the master input file, (case.struct) for this system since both atoms occupy the same Wyckoff sites but with different proportions. I have looked through the mailing list and have not found anything particular regarding this type of problem. The atomic positions are given below:</div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px"><b><u>Atom</u></b><b style="font-size:12.8px"> <u>Wyckoff Site</u> <u> (x,y,z)</u></b></div><div style="font-size:12.8px"><b style="font-size:12.8px"><u><br></u></b></div><div style="font-size:12.8px">Al(1) 2<i>a</i> (0,0,0)</div><div style="font-size:12.8px">Al(2) 6<i>h</i> (0.4647,0.9294,0.25)</div><div style="font-size:12.8px">Al(3) 12<i>k </i>(0.1935,0.3870,0.9392)</div><div style="font-size:12.8px">0.6786Fe(1)+0.3114Ni(1) 2<i>d</i> (1/3,2/3,3/4)</div><div style="font-size:12.8px">0.6786Fe(2)+0.3114Ni(2) 6<i>h</i> (0.1256,0.2512,0.25)</div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px"> As seen above, the iron and nickel atoms occupy the Wyckoff sites at an approximate 2/1 (Fe/Ni) ratio. Your assistance towards constructing the case.struct file for this compound is truly appreciated.</div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px"><div style="font-size:12.8px">With regards,</div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px">Farshad Nejadsattari,</div><div style="font-size:12.8px">PhD candidate in condensed matter physics,</div><div style="font-size:12.8px">University of Ottawa, Canada</div><div><img src="https://ssl.gstatic.com/ui/v1/icons/mail/images/cleardot.gif"></div><div><div><img src="https://ssl.gstatic.com/ui/v1/icons/mail/images/cleardot.gif"></div></div><span><font color="#888888"><div style="font-size:12.8px"><br></div></font></span></div></div>
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