<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:arial,helvetica,sans-serif;font-size:10pt"><font size="3"><span style="font-family: times new roman,new york,times,serif;">Hello everyone,</span><br style="font-family: times new roman,new york,times,serif;"><br style="font-family: times new roman,new york,times,serif;"><span style="font-family: times new roman,new york,times,serif;">I am trying to study impurities in SiC bulk material. For this, I use a big unitcell of 2x2x2. I do not understand how to do a relaxation in this system, ie, which atoms should be kept fixed? I was thinking that the unitcell boundary atoms would automatically be kept fixed but that does not seem to be the case. Any help will be much appreciated.</span></font><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt;"><div style="font-family: times new roman,new york,times,serif; font-size:
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<div><font style="font-family: times new roman,new york,times,serif;" size="3"> </font><br></div></div><font size="3">-- </font><br><font size="3">Izaak Williamson</font><br>Research Assistant<br>Physics Department<br>Boise State University<br><br>
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