Dear Amin,<br><br>1 - Convergence should not depend on the structure. You can check it for any reasonable structure (obviously if you push two atoms inside each other you'll be forcing your pseudopotential reliability, but for normal, not optimized structures, with reasonably low forces, should work fine).<br>
<br>2 - Your energy convergence table looks normal to me. The question you should now ask is: for the purpose you are doing your calculation, how much precision do you need? Is it 10^-1, 10^-2, 10^-3 Ry? That answer will define the value of ecut you have to use.<br>
<br>Best,<br><br>Giovani M. Faccin<br>UFMS/Unicamp - Brazil<br><br><br><br><div class="gmail_quote">2011/6/14 Amin Torabi <span dir="ltr"><<a href="mailto:amin.torabi@gmail.com">amin.torabi@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div>Dear experts!</div><div><br></div>
<div>Could you please have a look at my input file, attached to this email.</div><div><br></div><div>My main problem is that I expect the total energy to converge at lower ecutwfc energy. ( or I am expecting too much?)</div>
<div><br></div><div><div>ecut energy</div><div>25 -38.36026321</div><div>
30 -38.44145201</div><div>
35 -38.49537648</div><div>40 -<a href="tel:38.53312799" value="+13853312799" target="_blank">38.53312799</a></div><div>45 -<a href="tel:38.55904483" value="+13855904483" target="_blank">38.55904483</a></div><div>
50 -<a href="tel:38.57650475" value="+13857650475" target="_blank">38.57650475</a></div><div>55 -<a href="tel:38.58840904" value="+13858840904" target="_blank">38.58840904</a></div><div>60 -<a href="tel:38.59670631" value="+13859670631" target="_blank">38.59670631</a></div>
<div>65 -38.60253103</div><div>70 -38.60653038</div>
<div>75 -38.60918176</div><div>80 -38.61090436</div><div>85 -38.61200805</div><div>90 -38.61269007</div><div>95 -38.61308582</div><div>100 -38.61329742</div></div><div><br></div><div><br></div><div>
<br></div><div>Notes: </div><div><br></div><div>1. Do I have to be at the minimum structure to check for convergence of ecut vs energy, or I can check the convergency from a non-optimized structure? </div><div><br></div>
<div>2. I used USPP for one of my atoms and NCPP for the other atom, and set ecutrho = 10*ecutwfc...</div>
<div><br></div><div><br></div><div><br></div><div>Many thanks in advance!</div></div>
</div><br></div>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Giovani<br>