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<blockquote type="cite"
cite="mid:643258202.29290119.1580059324691@mail.yahoo.com">
<div class="ydpe426b620yahoo-style-wrap" style="font-family:
Helvetica Neue, Helvetica, Arial, sans-serif; font-size: 13px;">
<div dir="ltr" data-setdir="false" style="font-family: Helvetica
Neue, Helvetica, Arial, sans-serif;"><b><font size="3"><span><span
style="font-family: Helvetica Neue, Helvetica, Arial,
sans-serif;"> the definition for the compound </span></span><span
style="color: rgb(51, 51, 51); font-family: Arial,
sans-serif;">a=b = 3.74 A </span>alpha = beta = 90
gamma = 120 </font></b></div>
<div dir="ltr" data-setdir="false" style=""><b><font size="3">for
AFM type I : i creat superstructure x super cell target
lattice H : x =1, y = 1 , Z =2 then x sgroup,
program define automatically the space group the same of
my original space group 156 without warrning <br>
</font></b></div>
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</blockquote>
<p><font color="#000080">As you have described above (for Z=2), your
attempt at creating a supercell has failed as "x sgroup"
collapsed the supercell structure back to the non-supercell
structure.</font></p>
<p><font color="#000080">As mentioned on the FAQ page for supercell
construction, you need to displace an atom, change an atom, or
use a special label:</font><br>
</p>
<p><font color="#000080"><a class="moz-txt-link-freetext" href="http://susi.theochem.tuwien.ac.at/reg_user/faq/supercells.html">http://susi.theochem.tuwien.ac.at/reg_user/faq/supercells.html</a></font></p>
<p><font color="#000080">In order to keep the supercell without "x
sgroup" reducing it back to the original structure, refer to
previous posts in the mailing list archive about breaking the
symmetry. A few of the many posts about that as examples are at
the three links below:<br>
</font></p>
<font color="#000080"><a class="moz-txt-link-freetext" href="https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg18380.html">https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg18380.html</a></font><br>
<font color="#000080"><a class="moz-txt-link-freetext" href="https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg01866.html">https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg01866.html</a></font><br>
<font color="#000080"><a class="moz-txt-link-freetext" href="https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg15517.html">https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg15517.html</a></font>
<p><font color="#000080"><br>
</font></p>
<blockquote type="cite"
cite="mid:643258202.29290119.1580059324691@mail.yahoo.com">
<div class="ydpe426b620yahoo-style-wrap" style="font-family:
Helvetica Neue, Helvetica, Arial, sans-serif; font-size: 13px;">
<div dir="ltr" data-setdir="false" style=""><b><font size="3">but
when try to do it for type II : x super cell P <span><span
style="color: rgb(0, 0, 0); font-family: Helvetica
Neue, Helvetica, Arial, sans-serif;">: x =1, y = 1
, Z =1 x sgroup could not define the space group <br>
</span></span></font></b></div>
</div>
</blockquote>
<p><font color="#000080">In section "3.12 Setting up a new case" on
page 29 in the WIEN2k 19.1 usersguide [
<a class="moz-txt-link-freetext" href="http://susi.theochem.tuwien.ac.at/reg_user/textbooks/usersguide.pdf">http://susi.theochem.tuwien.ac.at/reg_user/textbooks/usersguide.pdf</a>
], there is the statement:<br>
<br>
"Alternatively with the new StructGen you can specify the
spacegroup and only the inequivalent positions. The equivalent
ones will be generated automatically."<br>
</font></p>
<p><font color="#000080">This means spacegroups in WIEN2k are
defined according to the inequivalent positions and not by the
equivalent positions. <br>
</font></p>
<p><font color="#000080">For the case above (Z=1), it is likely that
"x supercell" found some </font><font color="#000080"><font
color="#000080">equivalent positions in the original structure
and automatically added </font></font><font color="#000080"><font
color="#000080"><font color="#000080">special labels to them </font>changing
them into </font></font><font color="#000080"><font
color="#000080"><font color="#000080">inequivalent positions.
Thus, a supercell structure was successfully created. If
you want the supercell structure to reduce back to the
original structure, you would likely just need to remove all
or some of the special labels in StructGen before running "x
sgroup".<br>
</font></font></font></p>
<p><font color="#000080">For understanding the inequivalent and
equivalent positions with WIEN2k spacegroups, the example in the
post at the following link might helpful:<br>
<br>
<a class="moz-txt-link-freetext" href="http://zeus.theochem.tuwien.ac.at/pipermail/wien/2013-January/018171.html">http://zeus.theochem.tuwien.ac.at/pipermail/wien/2013-January/018171.html</a></font><br>
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