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If you know the form of the basic repeating unit (The un-doped
zincblende structure would be a good place to start), it may be
useful to use a molecule building program that has tools designed
for periodic systems. I have had success with gaussview; the GUI is
relatively intuitive and the coordinates stored in the .com file of
the supercell you create can be copied directly into the
corresponding section of the PW script (though be mindful of what
length units are being used). The key to gview is the PBC (periodic
boundary conditions) menu; there are several tutorials online with
detailed instructions regarding this part of the program. If
gaussview isn't available, I have heard good reviews of other
programs that may have similar or even better features - the one
that comes to mind is Avogadro but I'm sure there are others too. <br>
<br>
All that being said, I agree with professor Baroni that trying the
construction by hand is educational; as a new user of QE I tried by
hand a couple times for different crystal faces before 'cheating'
and using a program.<br>
<br>
Best of luck,<br>
<br>
Alex Shearer<br>
C.B. Harris Group<br>
University of California, Berkeley<br>
<br>
<br>
<br>
On 12/15/2011 1:11 AM, Stefano Baroni wrote:
<blockquote cite="mid:C38A4ED5-C927-4CBA-B967-1DA4EE740188@sissa.it"
type="cite">The same way you would "by hands". First draw
(physically with pencil and paper, or just mentally if you have a
good 3D imagination) a zincblende crystal structure with many unit
cells repeated in the three dimensions. Give different atoms
different colors. ZnSe can be colored with just two colors (say,
green and red, plus possibly black to draw bonds). Then highlight
the atoms that you want to turn into impurities using a different
color (say, blue), arranging them in periodic array (i.e. one
every 2/3/you-name-it elementary cells). Which crystal structure
has the artificial crystal you have built? The unit cell of this
artificial crystal will be your unit cell: it will contain many
atoms ... Do it by yourself: you will learn a lot ... (and it may
be fun!) - SB
<div><br>
<div>
<div>On Dec 15, 2011, at 9:19 AM, bamidele ibrahim wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">
<div>
<div style="color:; background-color:; font-family:times
new roman, new york, times, serif;font-size:12pt">
<div><span>Dear all,</span></div>
<div><span> I have been working on series of zinc
blende semiconductors materials in recent time. <br>
</span></div>
<div><span>I am now interested in doping some of the
compound with differents element in other to alter</span></div>
<div><span>the crystal structures(i.e introducing
impurities). I know i need to build a supercell for
my compound but, <br>
</span></div>
<div><span>i don't understand how to do it. I went
through all the examples files, but none was able to
give the information. I will</span></div>
<div><span>be delighted if you can all come to my aid.
for example ZnSe with atomic position of (0,0,0) and
(0.25,0.25,0.25). <br>
</span></div>
<div><span>How do i build a supercell for this compound?
</span></div>
<div> </div>
<div>Adetunji Bamidele Ibrahim<br>
Department of physics,University of Agriculture,<br>
Abeokuta, Ogun State,Nigeria.</div>
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