<p>With PBE they normally are too large by a few percent. If it really matters WC amd PBEsol are often better for lattice parameters, although they are also slightly more covalent.</p>
<p>---------------------------<br>
Professor Laurence Marks<br>
Department of Materials Science and Engineering<br>
Northwestern University<br>
<a href="http://www.numis.northwestern.edu">www.numis.northwestern.edu</a> 1-847-491-3996<br>
"Research is to see what everybody else has seen, and to think what nobody else has thought"<br>
Albert Szent-Gyorgi<br>
</p>
<div class="gmail_quote">On Apr 2, 2012 9:28 AM, "Souheyla Mamoun" <<a href="mailto:mamoun_souheyla@yahoo.fr">mamoun_souheyla@yahoo.fr</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div style="font-size:14pt;font-family:times new roman,new york,times,serif"><div><span>Dear all</span></div><div><span><br></span></div><div><span>I try to get the optimized lattice parameters a and c of hexagonal structure with space group 161 R3c using both of the volume and c/a optimizations. My obtained results are not comparable (too great) to the experimental and theoretical data. </span></div>
<div><span>Can you show me the procedure of optimization with relaxation, please?</span></div><div><span><br></span></div><div> </div><div><font style="color:rgb(0,0,191)" size="4"><span style="font-style:italic">Souheyla </span></font><br>
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