Hi Ali<br>In order to speed up the optimization procedure, it might be possible to optimize ecut and kpoint in a smaller system. For example if you want to do any surface or interface supercell calculations, I think it is enough to optimize ecut in the corresponding bulk materials. About kpoint you have to be more careful. The bulk optimized kpoint should be transferred to supercell calculation by taking into account the ratio of lattice parameters. I mean if a supercell lattice parameter is twice the bulk lattice parameter, then half of the number of bulk kpoint in the corresponding direction should be used in the supercell calculation. I think it is still better to verify the accuracy of kpoint by doing some supercell calculations in a denser kmesh.<br>
Kind regards<br>Javad Hashemifar<br><br><div class="gmail_quote">On Wed, Jul 15, 2009 at 5:51 PM, ali kazempour <span dir="ltr"><<a href="mailto:kazempoor2000@yahoo.com">kazempoor2000@yahoo.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><table border="0" cellpadding="0" cellspacing="0"><tbody><tr><td style="font-family: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-size: inherit; line-height: inherit; font-size-adjust: inherit; font-stretch: inherit;" valign="top">
<br>Dear all<br>For first step calculation, we know that the optimization of <span>ecut</span> and kpoint is <span>necessary . But I use norm conserving pseudopotential that the check of convergency with respect to total energy is time consuming. Is any parameter except total energy that can i put treshold on its convergency or not?<br>
thanks a lot </span> <br>Ali Kazempour<br>
Physics department, Isfahan University of Technology<br>
84156 Isfahan, Iran. Tel-1: +98 311 391 3733<br>
Fax: +98 311 391 2376 Tel-2: +98 311 391 2375</td></tr></tbody></table><br>
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<br></blockquote></div><br><br clear="all"><br>-- <br>======================================<br>Seyed Javad Hashemifar<br>Physics Department, Isfahan University of Technology<br>84156-83111 Isfahan, Iran<br>Tel: +98 311 391 2375 Fax:+98 311 3912376<br>
Email: <a href="mailto:hashemifar@cc.iut.ac.ir">hashemifar@cc.iut.ac.ir</a><br>Homepage: <a href="http://hashemifar.iut.ac.ir">http://hashemifar.iut.ac.ir</a><br>---------------------------------------------------------------------------<br>