<font size="2"><font face="comic sans ms,sans-serif">yeah, i think you are right. but what really matters is how to set ibrav in pwscf. <br></font></font><a name="id3900439"></a><pre> ibrav structure celldm(2)-celldm(6)<br>
<a href="goog_798003211" name="id3900439"></a><pre> 6 Tetragonal P (st) celldm(3)=c/a
7 Tetragonal I (bct) celldm(3)=c/a</pre><a name="id3900439"></a><pre>simple tetragonal (p)
====================
v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,c/a)
body centered tetragonal (i)
================================
v1 = (a/2)(1,-1,c/a), v2 = (a/2)(1,1,c/a), v3 = (a/2)(-1,-1,c/a).
<br>it seems that: if ibrav=6, then A=B≠C. if ibrav=7, then A=B=C.<br>but what i need is A≠B=C. i don't know if i can choose ibrav=6 or 7, and should i need to change the atoms position after i choose ibrav=6 or 7 ?</pre>
</pre><br clear="all"><span style="font-family:comic sans ms,sans-serif"><u>>>>>>>>>【this is an email sent by <b><span style="color:rgb(204, 0, 0)">tiankong</span></b>】</u></span><br>
<br><br><div class="gmail_quote">2011/6/24 GAO Zhe <span dir="ltr"><<a href="mailto:flux_ray12@163.com">flux_ray12@163.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
In your case, this structure must be simple tetragonal or body centered tetragonal. Please check your model more carefully from PDF-card or ICSD database.<br>P.S.: the choice of ibrav depends on the knowledge of crystallography, please learn it before you do ab-initio calculation, since symmetry is a very important and foundamental thing in this area.<br>
<font color="#888888"><div>--<br>GAO Zhe<br>CMC Lab, MSE, SNU, Seoul, S.Korea<br>
</div></font><div><div></div><div class="h5"><br>At 2011-06-24 15:25:10，"tian kong" <<a href="mailto:thisisasafeaccount@gmail.com" target="_blank">thisisasafeaccount@gmail.com</a>> wrote:<br> <blockquote style="padding-left:1ex;margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204, 204, 204)">
<font size="2"><font face="comic sans ms,sans-serif">i have read the help document about INPUT_PW.htm again and again, but since i'm a newbie, i still don't know whice one i should choose. can you help me?<br>here is the problem:<br>
A=10, B=C=8, cosAB=cosBC=cosAC=0.<br>can you tell me ibrav=?<br>thx a lot !!!<br clear="all"></font></font><span style="font-family:comic sans ms,sans-serif"><u>>>>>>>>>【this is an email sent by <b><span style="color:rgb(204, 0, 0)">tiankong</span></b>】</u></span><br>
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