<br><br><div class="gmail_quote">On Fri, Feb 3, 2012 at 2:59 AM, berber mo <span dir="ltr"><<a href="mailto:berbermohamed@yahoo.fr">berbermohamed@yahoo.fr</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div><div style="color:rgb(0,0,0);background-color:rgb(255,255,255);font-family:verdana,helvetica,sans-serif;font-size:12pt"><div><div><div><div style="color:rgb(0,0,0);background-color:rgb(255,255,255);font-family:verdana,helvetica,sans-serif;font-size:12pt">
<div><div><div><div style="color:rgb(0,0,0);background-color:rgb(255,255,255);font-family:verdana,helvetica,sans-serif;font-size:24pt"><div><font size="3"><span lang="en"><span>I work on wien2k 8 and i have problem with volume optimization .<br>
</span></span></font></div><font size="4"><span lang="en"><span> <font>I would like</font></span> <span>to know</span> <span>in detail
 how to</span> <span>optimize the volume</span></span></font><div><font size="3"><span lang="en"><span></span><span>a =</span>15.95 u.a      
         <span>b</span> <span>=</span> 19.53 u.a</span><span lang="en">                            <span>c</span> <span>=</span>15.95 u.a<br> <span></span><span>alpha=90
 °                </span><span> </span> <span>beta</span> <span>=90 °                                 </span> <span>gamma =144.73 °</span></span></font></div></div></div></div></div></div></div></div></div></div></div></blockquote>
<div> </div><div>The information you provided is very less. As far as I can understand 
this is the input that you want to give and then see the optimized 
structure with optimized volume and atomic coordinates. since your alpha
 and beta are equal as well  "a" and "c" so I will suggest you to 
reorient (rotate the unit cell around x-axis by Pi/2 ) the cell such 
that your "b"  becomes "c" and "gamma" will become "alpha." So in the 
new unit cell you will have  (just check it carefully, I may be slightly
 wrong)<br>
<span lang="en"><span>a =</span>15.95 A°               <span>b</span> <span>=</span></span><span lang="en">15.95 </span><span lang="en">A° </span><span lang="en">                             <span>c</span> <span>=</span></span><span lang="en">19.53 A° </span><br>

<span lang="en"> <span></span><span>alpha=</span></span><span lang="en"><span>144.73 °</span></span><span lang="en"><span>          </span><span></span> <span>beta</span> <span>=90 °                                 </span> <span>gamma =</span></span><span lang="en"><span>90 °      </span></span><br>

With this cell you can use the option ibrav = 5 ( celldm4 = cos(alpha) ).<br><br>And next time you post on this forum please sign in your affiliation.  <br></div><blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div><div style="color:rgb(0,0,0);background-color:rgb(255,255,255);font-family:verdana,helvetica,sans-serif;font-size:12pt"><div><div><div><div style="color:rgb(0,0,0);background-color:rgb(255,255,255);font-family:verdana,helvetica,sans-serif;font-size:12pt">
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<br></blockquote></div><br><br clear="all"><br>-- <br>Regards,<br>MOHNISH,<br>-----------------------------------------------------------------<br>Mohnish Pandey<div>BTech-Mtech, IIT Kanpur<br>Senior Project Associate,<br>
Department of Chemical Engineering,<br>IIT KANPUR, UP, INDIA<br>-----------------------------------------------------------------</div><br>